Abstracts

Keynote papers

Biphasic reactions in microreactors

B. Ahmed-Omera (b), D. Barrow (b), T. Wirth (a) a Cardiff School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK b Laboratory for Applied Microsystems, Cardiff School of Engineering, Cardiff University, Cardiff, CF24 3TF, UK

Abstract

The contact between immiscible liquids in a microfluidic system creating segmented flow offers great potential in the study of biphasic reactions in organic chemistry with significant advantages with respect to conventional flask techniques. As organic solvents play a key role in many chemical processes within the pharmaceutical and chemical industry, there are many applications of biphasic reactions in different areas of chemistry. For a simple biphasic reactions, we show that the application of various reaction conditions in microreactors using segmented flow can dramatically increase the reaction rate, especially when microwave irradiation, sonication or phase transfer catalysis are combined with segmentation.

Engineered Self-assembly From Nano to Milli Scales

Karl F. Böhringer Department of Electrical Engineering, University of Washington, Seattle, WA 98195-2500, USA

Abstract

Self-assembly is the autonomous and spontaneous organization of components into patterns or structures. Self-assembly is ubiquitous in nature, e.g. in the growth of crystals and organisms, but also at macroscopic scales – it is nature’s prevalent paradigm for manufacturing. Self-assembly also provides the basis for important new industrial manufacturing techniques, especially for components at the milli, micro, and nano scales: their small sizes and large numbers scale unfavorably for common serial techniques but favorably for a new, massively parallel approach. We believe that self-assembling systems will be able to create complex, heterogeneous, non-periodic, three-dimensional devices in massively parallel production processes. Hence, our research investigates the scientific and engineering foundations of self-assembly processes for integrated micro/nanoelectromechanical systems (MEMS/NEMS).

Mircofabrication using a Single Mode Yb Fiber Laser

W. O’Neill, K. Li, Q. Hu, P. Chopra, J. Kanghee, A. Buntardjo Institute for Manufacturing, University of Cambridge, Cambridge, CB2 1RX, UK

Abstract

The advances in design, performance, cost reduction, and brightness for the modern Yb fiber laser have opened up the possibility of redefining the micro processing options for a range of semiconductor materials and micro fabrication production techniques at a wavelength of 1064nm. The usual laser of choice for micro electronics processing is the 532, 355, or 266 nm DPSS system. The provision of a new MOPA high brightness Yb based fiber laser configuration has provided a range of pulse parameters (10-200 ns FWHM), peak powers approaching ~ 2G Wcm^(-2) , and pulse repetition rates up to 500 kHz. These processing parameters offer a broad range of material response characteristics. This paper provides a preliminary analysis of the use of a Yb based fiber laser in the production of Si and Glassy Carbon microstructures and explores the potential of this source for low cost micromachining solutions.

Traceable measurement of areal surface texture

R.K. Leach, C. Giusca Industry & Innovation Division, National Physical Laboratory, Teddington TW11 0LW, UK

Abstract

There is a clear need in industry and academia for traceable areal surface texture measurements. To address this need traceable transfer artefacts and primary instrumentation are required. The National Physical Laboratory (NPL) is working on two projects – one to develop areal transfer artefacts and one to develop a traceable areal surface texture measuring instrument. The authors describe the development of the artefacts and instrument, and present some of the challenges that are still required to be able to offer an areal traceability measurement service to industry. The instrument has a working volume of 8 mm x 8 mm x 0.1 mm and uses a co-planar air-bearing slideway to move the sample. It also uses a novel vertical displacement measuring probe, incorporating an air-bearing and an electromagnetic force control mechanism. The motions of the slideway and the probe are measured by laser interferometers thus ensuring traceability of the measurements to the definition of the metre. The artefacts were manufactured using a range of machining technologies and in a range of geometries suitable for stylus and optical based instruments.

Utilising Electrochemical Deposition for Micro Manufacturing

Peter T. Tang IPU Manufacturing, Kemitorvet 204, 2800 Kgs. Lyngby, Denmark

Abstract

Electrochemical deposition, comprising both electroplating and electroless plating, plays an important role as an indispensable process family utilised in many micro manufacturing process chains. Advantages of electrochemical deposition, such as deposition speed, relatively inexpensive equipment, reliability, the large amount of available processes as well as the almost atom-by-atom replication of a given substrate, has given the technology its present position within microelectronics, surface treatment and recently also micro- and nano-manufacturing. The present paper will briefly describe all the major disciplines of electrochemical deposition, as well as some of the problems and challenges that are usually associated with the different deposition processes. Finally are two applications, an all-nickel AFM cantilever and a new process chain for fabrication of tool inserts for injections moulding, described in some detail.

Q2M Special Session

Batch Fabrication Methods for Polymer Based Active Microsystems using Hot Embossing and Transfer Bonding Technologies

T. Grund, M. Heckele and M. Kohl Forschungszentrum Karlsruhe GmbH, Institute for Microstructure Technology (IMT),Postfach 3640, 76021 Karlsruhe, Germany

Abstract

A batch compatible process flow to overcome the costly piece by piece assembly of hybrid microsystems is shown. Hot embossing is used to fabricate microstructured polymer layers. Wafer scale compatible bonding tasks are carried out by ultrasonic welding and heat activated bonding with micromachined bonding foils. As demonstrator device, a shape memory alloy (SMA) actuated polymer microvalve is introduced. The valve concept, fabrication technologies and device characteristics are discussed.

Fabrication of piezoelectric thick-film bimorph micro-actuators from bulk ceramics using batch-scale methods

R.P.Jourdain and S.A.Wilson Materials Department, School of Applied Sciences, Cranfield University, Cranfield, Bedfordshire, MK43 0AL, United Kingdom

Abstract

Piezoelectric ceramic films in the 20-60 micron thickness range are rarely employed today in commercial micro-mechanical devices, even though their expected force capability suggests that they are well suited to many micro-fluidic and micro-pneumatic applications. Some examples would be micro-scale fuel cells and micro-combustors. Head sliders, radio-frequency (RF) micro-switches and powered micro-optics are further potential application areas. These are only a few and the barriers in bringing them into reality are those of processing compatibility rather than commercial desirability. Such issues are being addressed in the EU Framework 6 Project ‘Q2M’, which focuses on batch-scale fabrication issues for high quality new micromechanical devices that are cost-effective and which have extended capabilities. This paper discusses a potential batch-scale production route for piezoelectric thick-film bimorph microactuators that combines ultra-precision grinding of ceramics and femto-second laser machining, along with standard micro-fabrication techniques such as wafer bonding. This new method has the key advantage that many different shapes and thicknesses of actuator can be made with only minor process changes, meaning that actuators can be designed to suit their intended application. It contrasts with current practice whereby micro-actuators are often designed around a limited range of standard components, with consequent reduction in their achievable performance. The examples used are a 6mm diameter plane-spiral bimorph actuator for integration into a polymeric micro-valve and 2-5mm long bimorph cantilevers intended for use in a new type of silicon ‘house’ micro-valve, with pneumatic applications.

Material aspects for batch integration of PZT thin films using transfer bonding technologies – Q2M development

D. Bhattacharyya (a), R. V. Wright (a), Q. Zhang (a), P.B. Kirby (a), R. Guerre (b), U. Drechsler (b), M. Despont (b), F. Saharil (c), J.Oberhammer (c) (a) Materials Department, Cranfield University, Bedford MK43 0AL, UK (b) IBM Research Gmbh, Zurich Research Laboratory, Rueschlikon, Switzerland (c) Microsystem Technology Lab, KTH – Royal Institute of Technology, Stockholm, Sweden

Abstract

Transfer bonding is a reliable cost-efficient and low-temperature CMOS compatible technique which allows batch integration of materials whose incompatibility with Si makes them unsuitable for monolithic integration. In this heterogeneous device integration method the material and process incompatibilities inherent in Si IC technology are overcome by fabricating devices on separate substrates and then transferring them onto target (e.g. CMOS) wafers. Transfer bonding has great potential for integrating RF-MEMS devices incorporating, for example, high thermal budget materials such as PZT and PST or non-ferroelectric piezoelectrics such as AlN and ZnO into microwave ICs for enhanced systems performance. This paper presents an overview of technology developments within the EU sponsored project Q2M for the realization of transfer bonded piezoelectrically actuated RF MEMS switches and other components focusing in particular on material factors relating to growth of the piezoelectric films, in this case sol-gel deposited PZT, that restricts the choice of device layers and impact on PZT properties such as microstructure, film orientation and piezoelectric coefficients. New process developments such as hard masking of PZT pattern during RIE etching and its compatibility with polymer transfer bonding are discussed.

The integration of mono-crystalline silicon micro-mirrors on CMOS for SLM applications

F. Zimmera, M. Friedrichsa, M. Lapisac, F. Niklausc, M. Muellera, T. Bakkeb, H. Schenka, H. Laknera a Fraunhofer Institute for Photonic Microsystems (IPMS), Maria-Reiche-Str. 2, D-01109 Dresden, Germany b SINTEF Department of Mikrosystems and Nanotechnology, Gaustadalleen 23C, Oslo, Norway c KTH, The Royal Institute of Technology, Stockholm, Sweden

Abstract

Spatial light modulators (SLMs) based on micro-mirrors for use in DUV lithography and adaptive optics need very high mirror planarity as well as mirror stability. We will present results of new micro-mirror arrays, consisting of monocrystalline silicon, which is a material to fulfil these requirements. As all mirrors of the SLM can be separately activated by an underlying CMOS circuit, the integration of CMOS and MEMS must be achieved, which results in certain restrictions on processing temperatures and the compatibility of materials. Therefore a special low temperature bonding technology has been developed, using an adhesive polymer. This technique provides the transfer of a 300nm thin mono-crystalline silicon layer to the CMOS wafer using only 250°C. First silicon micro-mirrors have been made and characterized using pure adhesive polymer (PMGI), improvements using a mix of an inorganic material with a thin bond-polymer benzocyclobutene BCB) on top are in development. Both approaches and their results will be discussed and presented in detail.

Towards Batch Integration of SMA into Microsystems: An Actuator Prototype

D. Clausi, J. Peirs, D. Reynaerts Katholieke Universiteit Leuven, Department of Mechanical Engineering, Division PMA

Abstract

Shape Memory Alloys have a considerable potential for integration into microsystems, where scaling down of their size allows favorable exploitation of the intrinsic adaptive capabilities, providing an actuation mechanism for applications (e.g. micropneumatics) requiring large force control and large actuator stroke. However, the implementation of these materials into actual structures is rather complex and mostly confined to depositing thin NiTi films onto certain target substrates, resulting in devices having a relatively high cost-per-piece. This paper is aimed at investigating a novel approach for batch integration of SMA to microactuators, which might provide a cost-effective alternative to thin film technology while enhancing functional properties and design flexibility. Indicative requirements for the actuator design have been drawn from typical microvalve applications. In order to evaluate the actuator performance, brass microcantilevers have been produced, with prestrained SMA thin wires bonded on top of them, eccentrically with respect to the cantilever’s neutral plane. The activation of SMA element is obtained by direct heating through electrical current. The bending actuation of the cantilever leads to large strokes, expected to match the requirements of a wide range of applications.

Wafer-scale manufacturing of robust trimorph bulk SMA microactuators

N. Sandström (a), S. Braun (a), T. Grund (b), G. Stemme (a), M. Kohl (b), W. van der Wijngaart (a) a Microsystem Technology Lab, KTH - Royal Institute of Technology, Stockholm, SWEDEN b Institut für Mikrostrukturtechnik, Forschungszentrum Karlsruhe GmbH, Karlsruhe, GERMANY

Abstract

This paper demonstrates the concept of wafer-level fabrication and integration of robust bulk SMA microactuators based on adhesive bonding of cold-rolled SMA sheets to silicon wafers. Contact printing of an adhesive polymer ensures a selective bonding when transferring full SMA sheets to silicon structures on a patterned wafer. The induced stress of a thin dielectric film deposited on top of the SMA sheet ensures a stable and built-in reset mechanism of the actuators. The trimorph microactuators can be actuated by indirect resistive heating through a thin metal film. We report on the successful wafer-scale fabrication of actuator cantilevers and their characteristics. First test cantilevers show a cold-state deflection of 300 μm which, however, is limited by the silicon substrate. Upon heating, the cantilever shows a stroke of approx. 80 μm.

Components: fabrication and assembly technologies

A new tool for aligned micro-embossing and nano-imprinting

T.Rogers & I.Malmros Applied Microengineering Limited, Unit 8 Library Avenue, Didcot, Oxon.,OX11 0SG, UK

Abstract

A new multi-purpose MEMS fabrication tool is described. The tool enables in-situ aligned embossing and nanoimprinting, in addition to surface activation and aligned wafer bonding. De-embossing is also included in-situ via the use of vacuum chucks and chamber pressurisation. The multi-purpose tool enables the fabrication of bonded, embossed, multi-layer, micro-fluidic devices, for example PDMS structures on silicon, including the alignment of the embossed structure to any pre-existing patterning on the silicon. Examples are presented of various structures that have been made using the tool along with a description of the principles of operation.

Concept for Fluidic Self-Assembly of Micro-Parts Using Electro-Static Forces

J. Dalin (a), J. Wilde (a), A. Synodinos (b), P. Lazarou (b)and N. Aspragathos (b) (a) University of Freiburg – IMTEK, Department of Microsystems Engineering, Georges-Köhler Allee 103, 79110, Freiburg, Germany, contact: Johan.Dalin@imtek.uni-freiburg.de (b) Robotics Group, Department of Mechanical Engineering and Aeronautics, University of Patras, Greece, contact: Lazarou@mech.upatras.gr

Abstract

Self-assembly is relatively unused in industrial micro-fabrication, although it offers opportunities to simplify processes and to lower manufacturing costs. A variety of self-assembly procedures have been introduced that take advantage of various forces, e.g. capillary, gravitational, electro-static. In this paper a concept for the alignment of micro-parts on a substrate using fluidic-self-assembly with electro-static attraction is presented. Further, FEM-simulations for the electro-static alignment force are performed and its dependence on several geometric parameters, e.g. the width of the binding sites and the distance between micro-part and substrate at the binding sites, is investigated. Based on results an analytic model is extracted. Furthermore, simulations are also performed to estimate capillary alignment forces, acting on micro-parts that are self-aligned. Finally, the magnitude of electro-static and capillary forces is compared. This novel assembly concept, where the alignment of the component at the binding site is achieved due to electro-static energy minimisation and, optionally, in combination with capillary alignment, could be beneficial in the manufacturing of heterogeneously integrated MEMS, such as optical and RF micro-systems.

Concept for Packaging of a Silicon based Biochip

T. Velten (a), M. Biehl (a), T. Knoll (a), W. Haberer (a) (a) Fraunhofer Institute for Biomedical Engineering, Ensheimer Strasse 48, 66386 Sankt Ingbert, Germany

Abstract

We report on a concept for packaging of a silicon-based biochip for integration with a fluidic cartridge, thus forming a lab-on-chip (LOC). The biochip, which has dimensions of 2 mm x 2 mm, comprises a central membrane having a diameter of 200 μm, and 20 bond pads with metal tracks leading to the membrane. The packaged biochip provides a fluidic interface to the cartridge as well as electrical interfaces to the biochip electronics being located in a readout instrument. The packaging method ensures the strict separation between the wet sensing area and the electrical contacts. The challenge is that the biochip has a freely moving membrane, additionally with a delicate biological coating, and this membrane is positioned on the same side of the silicon chip as the bond pads for the electrical interconnection. For packaging, the biochip is mounted into a recess of a rigid printed circuit board (PCB). The biochip is electrically connected with the PCB using a proprietary MicroFlex interconnection (MFI) technology, thus resulting in a flat surface towards the reaction chamber of the fluid cartridge. After the realization of the electrical contacts between the sensor chip and the PCB, the entire chip is encapsulated with an epoxy layer, leaving the membrane of the biochip uncovered. To protect the membrane against the fluidic epoxy, a specially shaped silicone casting-mould is used. In a last step, the biochip with the epoxy layer is glued on the bottom side of the cartridge.

Electric fields in a hybrid batch fluidic micromanipulation concept

P. Lazarou (a), N.A. Aspragathos (a), E. Jung (b) (a) Robotics Group, Department of Mechanical Engineering and Aeronautics, University of Patras, Patras T.K. 26500, Greece (b) Chip Interconnection Technologies, Fraunhofer IZM Berlin, Germany

Abstract

Micromanipulation is a very important issue in several fields of technology (microelectronics, optoelectronics & MEMS device packaging). Current implementations do not provide both sub-micron accuracy and movement of parts over centimeter-scale to a ~100μm final alignment precision. A micropart-inside-a-liquid-droplet manipulation concept that manages to bridge the gap from meso via the micro to the sub-micron scale in a fully contained process has been previously introduced by integrating the phenomena of electrowetting, dielectrophoresis and fluidic self-assembly. In this paper, an investigation of the electric fields that drive the manipulation of the droplet and micropart during the stages of electrowettng and dielectrophoresis is presented. Information for critical factors such as electrostatic force, Maxwell stress and surface charge density distribution is provided. Their effect on the manipulation process is verified, in accordance to theory.

Fabrication of stainless steel micro components using softlithography

Mohamed Imbaby (a), Kyle Jiang (a), Isaac Chang (b) (a) School of Mechanical engineering, University of Birmingham, Edgbaston, Birmingham, UK (b) School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, UK

Abstract

316-L stainless steel has good mechanical properties and has been widely employed for making different devices. This paper presents a study for making micro 316-L stainless steel components by soft lithography in combination with powder metallurgical processes. The process involves producing deep and solid micro moulds using SU-8 photo resist, making soft replica of the moulds using silicon rubber (PDMS), forming green patterns by filling stainless steel slurry into the PDMS moulds. The green parts are de-moulded, de-bound, and finally sintered in tube furnace including nitrogen atmosphere to obtain the final micro parts. The resultant micro components show good quality micro parts with complex geometry. The density of the sintered parts reaches 91.5% of the theoretical one and the linear shrinkage of the micro components after sintering is investigated and it is found to be dependent on the percentage of the solid loading in the green patterns. The fabrication process is described in detail and the results of characterization in shrinkage and density have been analysed.

Flexible microfluidics based on commercial SU8 foils

Chantal Khan Malek and Laurent Robert Institute FEMTO-ST/Dpt. MN2S, CNRS UMR 6174, 32 Av. de l’Observatoire, 25044 Besançon, FRANCE

Abstract

Polymer-based microfabrication technologies are gaining momentum as they enable low cost fabrication of a variety of microsystems, with major developments in optical and microfluidic systems. The use of dry film resist for microsystem applications is briefly reviewed. A method based on the lamination of commercial SU8 dry films and photolithography for the formation of flexible thin film micro-devices is presented. Fast prototyping of multi-layer microfluidic simple chips with embedded channels is reported.

High Density Interconnections Fabrication by UV Lasers Microprocessing of Microvias and Microstructures

D. Ulieru (a), Alina Matei (b), Elena Ulieru (c), A. Tantau (c), Florin Babarada (d) (a) ROMES S.A., 126A, Iancu Nicolae Str., Bucharest, 72996, ROMANIA (b) National Institute for Research and Development in Microtechnologies, 32B,Erou Iancu Nicolae Str., Bucharest, 077190, ROMANIA (c) SITEX 45 SRL, 114, Ghica Tei Blvd., bl. 40, ap. 2, Dept. 2, Bucharest 72235, ROMANIA (d) “Politehnica” University of Bucharest, Splaiul Independentei Str., No. 313, Bucharest 060042, ROMANIA

Abstract

The strong evolution of electronic packaging in the field of high performance hand held electronic products involves, from the fabrication point of view, to manufacture small, lightweight, reliable and, very important too, cost effective electronic modules. In the last years new techniques and technologies for production of rigid/flexible MCMtype multilayer were introduced. The manufacturers of laminate substrates are being challenged to realize boards with very good electrical and mechanical properties. In the past the biggest issues regarding vias and via capture pad sizes were only solderability and manufacturability. Today the vias density is also an important electrical issue. The more vias on a board are presented, the more discontinuities into PCB/MCM passive interconnection structure are placed. For High Density Interconnection (HDI) circuits design one solution is to reduce the via hole and the via capture pad, but still maintain manufacturability at board fabrication stage.The most indicated solution is to use UV laser microprocessing for HDI production.

Investigation of Material Compatibility for Embedding Stereolithography

T. Rechtenwald (a), A. Kopczynska (b), E. Schmachtenberg (b), M. Devrient (a), T. Frick (a), M. Schmidt (a) (a) Bayerisches Laserzentrum GmbH, Konrad-Zuse-Str. 2-6, 91052 Erlangen, Germany (b) Lehrstuhl für Kunststofftechnik, Friedrich-Alexander Universität, Erlangen, Germany

Abstract

Decreasing sales figures and increasing demand of different variants at the same time, as well as the desire of a short time to market pose a challenge for nowadays manufacturing technology. In this context, a new flexible production technology for mechatronical devices, which include also optical functions, called Embedding Stereolithography (eSLA) is introduced. eSLA combines the flexibility to automatically generated inner and outer complex geometries of conventional SLA with embedded functional components, which are conducted by generative manufactured electrical and/or optical structures. To form a rugged mechatronical device out of mechanic and/or electronic parts by eSLA a sufficient wetting of the used components by the processed liquid photopolymer is needed. Therefore the surface tension and viscosity of different photopolymers is measured and compared to surface energies and surface roughness of relevant component materials. Afterwards the characteristics of wetting of the chosen photopolymers on these materials are discussed.

Large-area metal-coated dielectric nanopillar array for excitation of surface plasmon resonance

X. Chen, K. Jiang Micro Engineering and Nanotechnology Group, Department of Mechanical Engineering, University of Birmingham, B15 2TT, UK

Abstract

Many of current techniques are not suitable for the fabrication of metallic nanostructure on the scale of usual optical coatings at reasonable fabrication cost and time. A fabrication process for producing large-area metalcoated periodic nanopillars is presented. A hybrid metallic nanostructure array was obtained by depositing a silver film with a thickness of ~40 nm on the fused silica nanopillars with an in-plane diameter of ~140 nm and out-ofplane height of ~130 nm, which was fabricated by a combination of interference lithography, metal deposition and etching. There are two peaks in the extinction spectrum of the p-polarized incident light, one at 585.3 nm and the other 493.6 nm. The shift of the higher peak is 32.9 nm (a red-shift), while that of the lower peak is 42.3 nm (a blue-shift) with the addition of absolute ethanol on the sample surface. Such structure was used to monitor the evaporation process of the absolute ethanol on the sample surface. It was found that narrowest extinction peak appears at normal incidence, while the polarization of the incident light does not affect the experimental result due to the symmetrical distribution of the nanostructures. The fabrication process and unique optical properties of the structure array are expected to be suitable for the development of high-throughput ultrasensitive chemical sensor arrays.

Manufacturing and replication of cell aligning micro structures

C. Brecher (a),(b), R. Klar (b), F. Pretzsch (b), C. Wenzel (b) (a) Werkzeugmaschinenlabor (WZL), RWTH Aachen University, Germany (b) Fraunhofer-Institute for Production Technology Aachen, Germany

Abstract

Biotechnology is becoming more and more important and is influencing our everyday life. One of the most important advantages will become the manufacturing of mass customized cells also known as tissue engineering. To optimize and shorten the cell growth, micro structures have shown an important impact on the cell division, alignment and cell differentiation. This paper deals with the manufacturing of micro structured moulds by diamond machining and the successive replication process to create bio functional surfaces provided with micro structures. While the fabrication of micro structures by diamond machining is an expensive and long lasting process the replication of bio functional surfaces by hot embossing allows the cost efficient production of these surfaces. Compared to lithography processes, diamond machining is very flexible and offers next to 2D or 2 1/2D geometries real 3D forms to copy invivo conditions for in-vitro cell replication processes. One of the main advantages of diamond machining is the flexibility to diversify the shape of micro structures rapidly to investigate the cell - substrate - interaction down to the micrometer range.

Manufacturing of Versatile Ceramic or Metal Micro Components by Powder Injection Moulding

V. Piotter, K. Plewa, J. Prokop, A. Ruh, H.-J. Ritzhaupt-Kleissl, J. Hausselt Forschungszentrum Karlsruhe, Institute for Materials Research III P.O. Box 3640, 76021 Karlsruhe, Germany

Abstract

Although microsystems technologies products have been steadily launched worldwide markets the development and improvement of manufacturing processes suitable for medium or large-scale production is still one of the most important prerequisites. A well-known technology to meet such demands is micro injection moulding which has already reached an industrial viable status for polymeric materials. Nevertheless, there is still a lack of methods for the processing of materials with a wider range of properties. A promising option to close this gap, development of the so-called MicroPIM process to facilitate the fabrication of metal and ceramic micro components was started. Presently, the smallest dimensions achievable are 25-50μm of part thickness or minimum structural details of less than 5μm. Theoretical densities of up to 99% were achieved depending on the particular powder applied. As further improvement, the technology to produce rotational-symmetric parts by making use of a special head spindle system has been developed. To enlarge the application possibilities of MicroPIM further, micro two-component injection moulding enables, for example, the fabrication of micro components consisting of two ceramic or metal materials with different physical properties and, not less important, significantly minimises assembly expenditure.

Microfabrication of Components for a Novel Biomimetic Neurological Endoscope

A. Schneider (a), L. Frasson (b), T. Parittotokkaporn (c), F. M. Rodriguez Y Baena (b), B. L. Davies (b), and S. E. Huq (a) (a) Science and Technology Facilities Council, Rutherford Appleton Laboratory, Technology – Central Microstructure Facility, Harwell Science and Innovation Campus, Didcot, OX11 0QX, UK (b) Mechatronics in Medicine Lab., Depart. of Mechanical Engineering., Imperial College, London, SW7 2AZ, UK (c) Institute of Biomedical Engineering, B 422 Bessemer Building, Imperial College, London SW7 2AZ, UK

Abstract

The development of a novel biomimetic neurosurgical probe is inspired by nature. Some insects have spines with a unique surface texture which enables them to penetrate tissue more easily. This surface texture consists of cutting teeth and fin-like pockets on the spine. Instead of drilling, the insect slides its spine into the fibre through the reciprocating motion of independent segments. Applying the same or similar microtexture to a miniaturized neurosurgical endoscope could improve existing tools for brain surgery and brain biopsy. The development of such endoscope could minimize the damage caused by inserting the probe whilst avoiding the risk of buckling, which is a common occurrence when thin flexible probes are axially loaded. To replicate the surface microtexture, teeth and fin-like high-aspect-ratio microstructures were fabricated. Different geometries of these fins and teeth were studied for insertion into tissue so that the texture could be characterized for friction and tribological interaction with tissue. For these tests, free-standing long and narrow strips with microstructures in up to 525 μm thick SU-8 were designed, fabricated, and mounted onto prototypes made by stereolithography. This paper focuses on the fabrication of the microtextured strips. The required geometry of these strips can cause considerable bending. The structures were investigated regarding fabrication and stress conditions.

Single- and multi-layer conductive patterns fabricated using M3D technology

B. Obliers-Hommrich (a), A. Fischer (b), H. Willeck (a), W. Eberhardt (a), H. Kück (b) (a) Hahn-Schickard-Institute of Microassembly Technology HSG-IMAT, Stuttgart, Germany (b) University of Stuttgart, Institute of Micro and Precision Engineering, Germany

Abstract

The continual trend of miniaturization and increasing complexity in the field of microelectronic devices pose a challenge for today’s manufacturing technology. The novel Maskless Mesoscale Material Deposition (M3D) manufacturing technology offers the potential for printing superfine circuitry as well as for the building up of multi-layer systems. Therefore it could be an interesting technology to meet the requirements of miniaturized systems. The M3D process depends on aerosol formation and uses aerodynamic focusing of aerosol streams for a high resolution deposition of colloidal suspensions and liquid raw material. Since M3D is a contactless and maskless Direct Write Technology, it also offers new possibilities for 3D devices. This paper will report on first results of depositing conductive and non conductive materials onto glass substrates as well as onto typical MID (Moulded Interconnect Devices) substrates. Furthermore it will present first multi-layer systems that have been fabricated using the M3D technology.

Towards automation in AFM based nanomanipulation and electron beam induced deposition for microstructuring

F. Krohs (a), T. Luttermann (a), C. Stolle (a), S. Fatikow (a), E. Brousseaub, S. Dimov (b) (a) Div. Microrobotics and Control Engin., Univ. of Oldenburg, Germany; (b) The Manufacturing Engineering Centre (MEC), Cardiff University, Wales

Abstract

To move towards complex assemblies at the micro- and nanoscale, manipulation processes have to be automated to increase throughput and accuracy. First, this paper addresses manipulation at the nanoscale by an AFM and second, automated electron beam induced deposition as a method for structuring at the microscale is presented. Nowadays, AFM based nanomanipulation still requires frequent user interaction and remains a very labor intensive task. Spatial uncertainties are identified as a major problem that prevents reliable automation of AFM based manipulation. Results of a novel particle filter based method for measuring thermal drift in an AFM system is presented and future applications for probabilistic methods are discussed. The automation of electron beam induced deposition (EBiD) for microstructuring purposes builds a multifunctional tool for additive structuring and also bonding inside an SEM. The presented system has the ability to create EBiD depositions from two different precursor materials by automatically executing predefined sequences. The automation includes the precursor flux control with the possibility to alternate between two materials, the deposition of points and lines at defined positions, as well as the ability to find and track already deposited structures with the use of digital image processing. This assures precise positioning of depositions relative to others even in cases of thermal or electrostatic drifting of the specimen substrate or the electron beam.

Ultrasonic welding of micro plastic parts

W. Michaeli (a), E. Haberstroh (b), W.-M. Hoffmann (a) (a) Institute of Plastics Processing (IKV), RWTH Aachen University, Aachen, Germany (b) Lectureship and Research Field of Rubber Technology, RWTH Aachen University, Germany

Abstract

Due to the ongoing miniaturisation in many industrial branches plastics are increasingly applied in microsystems technology. To guarantee the functionality of the system suitable joining processes must be applied to join separate components. Most of the welding processes commonly used for series production are not suitable for welding micro parts made from plastics, since either the mechanical or the thermal load of the joining partners during the welding process are too high. Only laser transmission welding and ultrasonic welding are applicable for welding complex micro components. Since with ultrasonic welding a certain frictional load of the components cannot be avoided totally with standard welding equipment, specially adapted machinery has to be used as it could be shown at the Institute of Plastics Processing (IKV) at RWTH Aachen University. While micro parts with two-dimensional weld seams have already been successfully welded in previous investigations, recent research deals with the ultrasonic welding of micro parts with a more complex three-dimensional weld seam geometry. It could be shown that for appropiate welding parameters this can be accomplished, whereby the mechanical load of the parts has to be kept as small as possible.

Wafer-scale transfer of nanoimprinted pattern into silicon substrates

G. Hubbard (1), S.J. Abbott (1), Q. Chen (2), D.W.E. Allsopp (2), W.N. Wang (2), C.R. Bowen (2), R. Stevens (2), A. Satka (3) D. Hasko (3), F, Uherek (3) and J. Kovac (3) (1) MacDermid Autotype Ltd, Grove Road, Wantage OX12 7BZ, England (2) Faculty of Engineering and Design, University of Bath BA2 7AY, England (3) International Laser Center, Ilkovicova 3, Bratislava 812 19, Slovakia

Abstract

Nanoimprinting provides a low cost alternative to Deep Ultra-Violet and electron beam lithography for producing deeply sub-micron features in semiconductor device fabrication. This paper presents a flexible nanoimprint process capable of wafer-scale pattern transfer into Si substrates. The technique is based on the novel concept of a disposable soft master with matching imprint resist formulations. Both of the resists developed enable the transfer of vertical sided, nearly flat bottomed features in Si substrates. The technique lends itself to large-scale low cost roll-toroll processing based on the concept of a disposable master. The process is a promising method for low-cost formation of photonic crystal structures in hard substrates and is potentially suitable for high volume production.

X-ray pattern analysis of electroplated two-component moulds used for the production of micro gear wheels

J. Prokop (a),(b), J. Lorenz (a), V. Piotter (a), H.-J. Ritzhaupt-Kleissl (a), A. Roch (a), and J. Haußelt (a),(b) (a) Forschungszentrum Karlsruhe GmbH, Institute for Materials Research III (IMF III) Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany (b) Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany

Abstract

A process for the fabrication of metal micro components by combining 2-component injection moulding with metal deposition by electroforming will be presented. To produce these 2-component polymer templates, an electrically conductive base plate is generated by injection moulding of electrically conductive carbon black-filled polymers. In a second injection moulding step microstructures consisting of insulating polymers are mounted onto these plates. The quasi-infinite conductivity gradient of such 2-component templates allows controlled electroplating to start from the base plate only, such that defect-free metal micro components can be achieved. The parameter set of the injection moulding process has been investigated by using an experimental method with an x-ray pattern analysis. Nearly defect-free electroplated micro parts could be fabricated by this process so far.

Metrology: inspection and characterisation methods 

Approaching a sub-micron capability index using a Werth Fibre Probe System WFP

Richard Thelen (a), Joachim Schulz (a), Pascal Meyer (a), Volker Sailea (a) (a) Institute for Microstructure Technology, Research Centre Karlsruhe, 76646 Eggenstein, Germany

Abstract

Reproducibility and precision of LIGA structures has been claimed in many publications, founded mainly on brilliant pictures. Because of the poor accessibility to the sidewalls many publications are based on surface measurements without including information about z depending aspects [1] and focus on reproducibility as measured close to the top. Often this neglects operator’s influence, short time and long time reproducibility, environmental effects on the CMM and others. Tactile optical metrology might help to overcome 2D measurements. Repeatability of tactile optical metrology at IMT was proven to be less than 0,3 μm over some months using ultra fine probes with less than 25 μm diameter. In addition DoE was used to determine the minimum deviation for best possible machine settings. Standard Deviation between 50 and 30 nm was measured. Compared to that, uncertainty remains about 1-2 μm for 3D measurements even with z maximum restricted to 1 mm [2]. Not enough to measure sub-μm product variation that is a typical benefit of LIGA products. Investigations were started at the Research Centre Karlsruhe to find out more about the effects influencing the measurements to explain why repeatability and capability do not match. Interaction between sample and sensor was the main reason. This was simulated and the results were used to reduce the uncertainty of the system. IMT elaborated a new strategy that improves the capability of a coordinate measurement machine CMM with tactile optical sensor for LIGA parts with sub μm variation.

How reliable are surface roughness measurements of micro-features? - Experiences of a Round Robin test within nine 4M laboratories

L. Mattsson (a), P. J. Bolt (b) , S. Azcarate (c), E. Brousseau (d), B. Fillon (e), C. Fowler (f), E. Gelink (b), C. Griffiths (d), C. Khan Malek (g), S. Marson (h), A. Retolaza (c), A. Schneider (f), A. Schoth (i), A. Temun (a), P. Tiquet (e), and G. Tosello (k) (a) KTH – the Royal Institute of Technology, Department of Production Engineering,School of Industrial Engineering and Management, SE-10044 Stockholm, Sweden (b) TNO Science and Industry, 5600 HE Eindhoven , The Netherlands (c) Tekniker Technological Center, 20600 Eibar, Spain (d) Cardiff University, Manufacturing Engineering Center (MEC), Cardiff CF 24 3AA, United Kingdom (e) French Atomic Energy Commission (CEA), Laboratory of Innovation for New Energy Technologies and Nanomaterials (LITEN), 38054, Grenoble, France (f) Science and Technology Facilities Council, Rutherford Appleton Laboratory (RAL), Technology – Central Microstructure Facility, Harewell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0QX, UK (g) FEMTO-ST Institute, CNRS UMR 6174, LPMO Department, 25044 Besancon Cedex, France (h) School of Applied Sciences, Cranfield University, Cranfield, Beds, MK43 0AL, UK (i) University of Freiburg, Institute of Microsystem Technology (IMTEK), 79110 Freiburg, Germany (k) Technical University of Denmark (DTU), Department of Manufacturing Engineering and Management (IPL), 2800 Kgs. Lyngby, Denmark

Abstract

Surface roughness of tiny micro machined features is not easy to verify. The statistical variation of the surface itself can be the limiting factor that hampers tolerance verification. In this paper we have studied this effect and we also test the performance of 10 different surface profilers over a very well specified surface area. For this area 6 profilers yielded the same result within a standard deviation window of ±6%. For other areas, on top of narrow bars and in narrow and deep channels, a much larger spread in the Round Robin results was found.

Measurement of frequency response of the bone ossicles in the sheep middle ear by the fiber-optic microphone

Z.V. Djinovic (a),(b), R. Pavelka (c), L. Manojlovic (b), D. Vujanic (b), M.C. Tomic (d) (a) Institute of Sensor and Actuator Systems, Vienna University of Technology, Vienna 1040, Austria (b) Integrated Microsystems Austria, Wiener Neustadt 2700, Austria (c) Schwerpunktkrankenhaus, 2700 Wr.Neustadt, Austria (d) Institut Bezbednosti, Belgrade 11000, Serbia

Abstract

In this paper we present a contactless technique for measurement of acoustic vibrations and frequency response of the bone ossicles in the sheep middle ear. This technique is based on high-coherence interferometry performed by a single mode fiber-optic sensing configuration with just one sensing fiber directed against the target. High-coherence light of 1310 nm wavelength has been impinging a retroreflective target that is firmly fixed upon the incus of the middle ear. We measured frequency response of the middle ear causing vibration of the incus by generation of air pressure from a well calibrated acoustic source in the range of 50 to 90 dB SPL and frequency from 250 Hz to 6 kHz.

Micro-ultrasonic metrology of multi-material electronic devices

R. Teti, P. De Santo Department of Materials and Production Engineering, University of Naples Federico II, Naples, Italy

Abstract

The main objective of this work is the investigation on micro-nondestructive evaluation (micro-NDE) metrology for dimensional measurement and quality control of multi-material electronic devices consisting of chipset tablet assemblies. The micro-NDE approach is based on ultrasonic (US) sensors in pulse-echo testing mode applied according to the full-volume immersion scan method that provides for the US axial tomography of the chipset tablet. The thickness of the multi-material chipset tablet assembly layers was evaluated through micro-US 2½ D geometrical measurements and the chipset tablet inter-layer integrity was critically assessed via micro feature US image analysis.

Novel materials: characterisation and processing 

3D micro and nanostructuring of an epoxy based resist by electron beam lithography

G. Rius, J. Bausells, C. Martín, A. Llobera and F. Pérez-Murano Institut de Microelectrònica de Barcelona, IMB-CNM-CSIC, Barcelona, SPAIN

Abstract

We present the results of producing three dimensional micro- and nanostructures on an epoxy based resist. Epoxy based resists are very interesting in microsystems technology for their good mechanical properties, that allow to produce high aspect ratio microstructures. We have optimized the definition of free standing structures by either using electron beam lithography alone or combining electron beam lithography and UV optical lithography. To tune the energy and dose of the electron beam exposure properly, Monte Carlo simulations are used.

An analysis of the effects of nanolayered nitride coatings on the lifetimes and wear of tungsten carbide micromilling tools

D. Zdebski (a), D.M. Allen (a), D.J.Stephenson (a), J. Hedge (a), C. Ducros (b) and F. Sanchette (b) (a) Precision Engineering Centre, Cranfield University, Bedford MK43 0AL, UK (b) CEA Grenoble, Labatoire des Technologies des Surfaces, 17 rue des Martyrs 38054 Grenoble CEDEX, France

Abstract

Micromilling is becoming increasingly important for a wide range of manufacturing tasks in the general field of microengineering, such as milling small channels in micromoulds designed for the fabrication of microfluidic devices by microinjection moulding of polymers. However, micromilling tools, often less than 1mm in diameter, are rather delicate, fracturing when forces become excessive and, consequently, micromilling can become an expensive process. In an attempt to increase tool lifetimes and reduce costs, micromilling forces have been measured with a microdynamometer and the effects of chromium nitride/titanium nitride and titanium aluminium nitride/titanium nitride coatings have been evaluated as an aid to decreasing tool wear and extending the lifetime of tungsten carbide micromilling tools. The surface finish of the milled workpiece has also been measured to monitor how tool wear affects the resultant milled surface.

Carbon nanotubes grown directly on printed electrode of electrochemical sensor

J. Prasek (a), J. Hubalek (a), M. Adamek (a), O. Jasek (b) (a) Department of Microelectronics, Brno University of Technology, Brno 60200, Czech Republic (b) Department of Physical Electronics, Masaryk University, Brno 60200, Czech Republic

Abstract

This paper is devoted to the area of electrochemical sensors. In this work several screen-printed thick-film electrodes are prepared. These electrodes are commonly used as the working electrodes of electrochemical sensors. The surface of the electrode has been modified with nanopatterned nanostructures. The nanostructures have been formed as vertically aligned carbon nanotubes that were grown directly on the screen-printed working electrode using plasma enhanced chemical vapour deposition method. The aim was to improve electrochemical properties of the electrode by creating homogeneous and high density carbon nanotubes directly on the thick-film layer. The created structures have been investigated by scanning electron microscopy. The electrochemical properties have been investigated by electrochemical detection of cadmium ions in aqueous solutions. The concentration of cadmium ions in units of μmol/L can be determined with the modified electrode.

Dielectric properties of hydroxyapatite based ceramics

J.P. Gittings (1), C.R.Bowen (1), I.G.Turner (1), A.C.E.Dent, F.R.Baxter (1), (2) and J.B. Chaudhuri (2) (1) Department of Mechanical Engineering, University of Bath,BATH, BA2 7AY. (2) Department of Chemical Engineering, University of Bath,BATH, BA2 7AY.

Abstract

This paper studies the ac conductivity and permittivity of hydroxyapatite based ceramics (HA) at temperatures from room temperature to 1000ºC. HA ceramics were prepared either as dense ceramics or in porous form with interconnected porosity and were sintered in either air or water vapour. Samples were thermally cycled to examine the influence of surface adsorbed water on conductivity and permittivity. Surface bound water was thought to contribute to conductivity for both dense and porous materials at temperature below 200ºC. At temperatures below 700ºC the permittivity and ac conductivity of HA was also influenced by the degree of dehydration and thermal history. At higher temperatures (700-1000ºC), bulk ionic conduction was dominant and activation energies are in the range of ~2eV, indicating that hydroxyl ions are responsible for conductivity.

DRIE of non-conventional materials: first results

Samuel Queste, Gwenn Ulliac, Jean-Claude Jeannot and Chantal Khan Malek Institute FEMTO-ST/Dpt. MN2S, CNRS UMR 6174, 32 Av. de l’Observatoire, 25044 Besançon, FRANCE

Abstract

High speed directional etching of non conventional materials is still insufficiently developed for producing high aspect ratio microstructures. Compared to deep silicon etching, the plasma etching of these materials has suffered from limitations in achievable depth, aspect ratio, verticality and smoothness of surfaces. Inductively coupled plasma (ICP) reactive ion etching (RIE) of quartz crystal, lithium niobate and glass was conducted using fluorine and fluorocarbon based plasma-chemical etching processes. Optimization of etched depth, verticality of the walls, etch rate, etch selectivity towards the etch mask, and surface smoothness was investigated and compared to results of the literature. Deep etching with nearly vertical walls was successfully demonstrated for all three materials.

Explosive welding of Ni- based amorphous foils for micro-tooling applications

R.M. Minev (a), S.S. Dimov (b), S.R. Koev (c), G.Lalev (b), N.H. Festchiev (a) (a) Department of Materials and Manufacturing Engineering, Rousse University, 8 Studentska, 7017 Rousse, Bulgaria (b) Manufacturing Engineering Center, Cardiff University, Cardiff, CF24 3AA, UK (c) BOM Ltd, Basarbovo, 7071 Rousse, Bulgaria

Abstract

In spite of the commercial advantages the available engineering materials for IC and MEMS processes are not able to meet the manufacturing demands for 3D high-aspect-ratio nano/micro structures and high precision. There is a group of energy assisted processes, such as laser ablation, e-beam and ion beam machining that could provide the needed high specific processing energy to create 3D microstructures. However, the required surface integrity of the manufactured nano/micro structures cannot be achieved without developing appropriate materials with adequate processing response. Thus, to broaden the range of micro-engineering products and multiply their capabilities the introduction of “novel” compatible amorphous or composite materials is required. The study presents the capability of the explosive welding technology to create a bimetallic sandwich with amorphous Ni-based alloys foils (40 μm thick) without affecting the structure of the materials. Direct patterning by Focused Ion Beam (FIB) was used to produce masters from these materials for injection moulding and hot embossing tools. It was demonstrated that high feature resolution and surface quality of the manufactured nano/micro structures can be easily achieved by employing this technological chain.

FT-IR study of nanosurface phenomena

I. Markova – Deneva University of Chemical Technology and Metallurgy –Sofia, 8 St. Kl. Ohridski blvd., 1756 Sofia, e-mail:vania@uctm.edu

Abstract

IR study of metal nanoparticles in amorphous or crystalline state obtained via water solution of metal salts by borohydride reduction with NaBH4, as well as of nanowires prepared using mesopore ceramic supports has been carried out. FT-IR spectra in mid-infrared region of visible spectrum (4000-400 cm-1) of these nanoscaled materials have been undertaken. IR spectroscopy possibilities have allowed to investigate the nanosurface phenomena and to prove the creation of different chemical bonds such as B-O, B-H, Si-O, O-H in surface atom groups. FT-IR spectra have provided information about the technological and hydrodynamic conditions such as a kind of the initial salt, a type of the reactor used (T, Y, A methods), different ceramic supports used (SiO2, SiMCM and ALMCM), different variants of the support introducing surface wetting), as well as about the nanosclaled materials composition, their structure state and nucleation.

Investigation of the mechanical behaviour of thin metal sheets using the hydraulic bulge test

A. Diehl, D. Staud, U. Engel Chair of Manufacturing Technology, University of Erlangen-Nuremberg Egerlandstr. 11, D-91058 Erlangen / Germany

Abstract

Ongoing miniaturisation leads to increasing complexity of micro parts linked with continuously decreasing development time. Hence, the demand for reliable material data and means to collect these data in a most efficient way is rising. Since the mechanical properties and thus material forming behaviour are dependent on the stress and strain conditions, the test methods have to be as close as possible to real conditions. Further, due to the so called size effects, data gathered from conventional length scale experiments cannot be used for the description of material used for parts with feature sizes in the micrometer range. In the present paper, the hydraulic bulge test as a means for the mechanical characterisation of thin metal sheets with thicknesses in the range of 25 μm to 500 μm is discussed and compared to data obtained by conventional tensile testing. Challenges due to the small sheet thickness are emphasized and the effect of strain rate on the flow curve is shown. The influence of geometric dimensions on the evaluation of the experiments is investigated by downscaling of the hydraulic bulge test. The material flow curves, as well as the forming limits are discussed in dependence of the sheet thickness.

Machining of polystyrene by UV laser radiation for patch clamping device fabrication

S. Wilson (a),(b), W.Pfleging (c), A. Welle (d), P.Kirby (b), M.Przylbyski (e) (a) Institute for Microstructure Technology, Forschungszentrum Karlsruhe, 76344 Eggenstein-L, DE (b) School of Applied Sciences., Cranfield University, Cranfield, Beds. MK43 0AL, UK (c) Institute for Materials Research 1, Forschungszentrum Karlsruhe, 76344 Eggenstein-L, DE (d) Institute for Biological Interfaces, Forschungszentrum Karlsruhe, 76344 Eggenstein-L, DE (e) ATL Lasertechnik GmbH, Burger Str. 48, 42929 Wermelskirchen, Germany

Abstract

Laser patterning is of interest for MST applications; direct ablation of polymer material for generating 2D and 3D shapes such as microfluidic channels, curved shapes or micro-holes and alternatively photo-induced change of chemical or physical surface properties. Correct laser choice and process parameters enables new approaches for the fabrication of lab-on-chip devices with integrated functionalities. Laser-assisted ablation and modification of polystyrene (PS) is introduced with respect to the fabrication of polymer devices for high throughput planar patch clamping - a method of measuring the electrical activity of a cell currently a focus for high throughput systems (HTS). There are currently no marketed systems using novel materials that have surface modifications for either individual cell placement, or for dealing with cell networks, a physiologically important consideration for tissue engineering and understanding cell to cell interactions. Within 4M, a design jointly proposed by FZK and Cranfield University for the fabrication of a polymer patch clamping system, laser micro-drilling of PS and subsequent surface functionalisation for cell adhesion has been investigated as a function of laser and process parameters. High power ArF laser with a pulse of 20 ns as well as high repetition ArF excimer laser sources with pulse lengths of 4-6 ns were used in order to study the influence of laser pulse length on laser drilling and laser induced surface modification. Micro-drilling of PS with diameters down to 1.5 μm have been demonstrated. Furthermore, localized formation of chemical structures suitable for improved single cell and cell network adhesion has been achieved on PS surfaces.

Micro Electrical Discharge Machining of Si3N4-based Ceramic Composites

K. Liu, J. Peirs, E. Ferraris, B. Lauwers, D. Reynaerts Afd. PMA, Department of Mechanical Engineering, Katholieke Universiteit Leuven, Leuven, BE-3001, Belgium

Abstract

The Electrical Discharge Machining (EDM) behaviour and machining properties of advanced engineering Si3N4-based ceramic composites Si3N4-TiN are investigated and discussed in this paper. Two types of EDM machining configurations, micro-EDM milling and die-sinking EDM, are employed in the investigation. Relaxation type of pulse is used, and the performances of EDM process in the form of material removal rate, tool wear and surface quality are studied. These tests result in a performance comparison and a discussion on the ceramic composites material removal mechanism. The feature of material removal mechanism is characterised as chemical decomposition of Si3N4 and TiN at elevated temperature rather than melting/evaporation. The generation of nitrogen gas bubbles leads to a porous and foamy top surface structure. Due to the ideal mechanical and physical property of Si3N4-TiN ceramic composites, an application example - a turbine impeller - as a crucial component in a micro power generation system is manufactured with obtained knowledge in both machining configurations.

Micro-extrusion of an ultrafine grained copper can

S. Geißdörfer (a), A. Rosochowski (b), L. Olejnik (c), U. Engel (a) (a) Chair of Manufacturing Technology, University of Erlangen-Nuremberg, Egerlandstrasse 11, 91058 Erlangen, Germany (b) Department of Design, Manufacture and Engineering Management, University of Strathclyde, 75 Montrose Street, Glasgow, United Kingdom, G1 1XJ (c) Institute of Materials Processing, Warsaw University of Technology, 85 Narbutta Street, 02-524 Warsaw, Poland

Abstract

Because of the well known virtues of low cost and high productivity, metal forming technology is well suited for mass production of metal micro-components. However, scaling down traditional metal forming processes proves to be problematic because, among other factors, the relatively coarse grain (CG) structure of micro-billets leads to nonuniform material flow and lack of repeatability during microforming. The aim of the presented study is to investigate a possibility of using an ultrafine grained (UFG) copper for micro-extrusion. The UFG version of Cu is produced by severe plastic deformation at room temperature using 4 and 8 passes of equal channel angular pressing (ECAP). The microstructure and compression properties of the UFG copper are investigated. For visualisation purposes, the microforming process of backward extrusion is carried out at room temperature using half cylindrical billets and transparent tools. The extrusion results, for billets subjected to 4 and 8 passes of ECAP, are compared in terms of the extrusion force, grain flow, shape representation and surface quality and show clearly that applying ultrafine grained material to microforming processes reduces scaling effects.

Micromachined silicon electrodes for electrochemical micromachining

C. Blattert (a), C. Müller (b), H. Reinecke (a),(b) (a) Hahn-Schickard-Gesellschaft e. V. Institute for Micromachining and Information Technology (HSG-IMIT),Villingen-Schwenningen, Germany (b) Laboratory for Process Technology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany

Abstract

Piracy and counterfeiting as well as retraceability demands of products such as plastic parts or tablets require new and innovative methods for unique product identification. An opportunity is the placement of microstructured codes in moulding tools. These tools are often made from materials that do not allow for highly precise micromachining by traditional technologies. Electrochemical machining (ECM) is a method for structuring construction materials such as steel or titanium. The current paper presents a new technology for the fabrication of microstructured tool electrodes for electrochemical machining by using highly doped silicon as electrode material. A simple and low priced fabrication of microstructured silicon electrodes with locally isolated areas is demonstrated by using wellestablished silicon processing technologies. Prototypes based on this new tool electrode technology are fabricated. Therewith electrochemical machining of microstructures in stainless steel is successfully demonstrated. Machining gaps down to 10 μm and average surface roughness of 60 nm are achieved. Typical rates of removal between 60 - 240 μm/min are reached. The local isolation of electrode areas advances the machining accuracy.

Micromachining of amorphous and crystalline Ni78B14Si8 alloys using micro-second and pico-second lasers

I. Quintana (1), T. Dobrev (3), A. Aranzabe (2), G. Lalev (3), S. Dimov (3) (1) CIC marGUNE. Pol. Ibaitarte 5, 20870; Elgoibar; Guipúzcoa, Spain (2) Manufacturing Processes Department, Fundación Tekniker, Av. Otaola 20, 2060, Eibar, Guipúzcoa, Spain (3) Manufacturing Engineering Centre, Cardiff University, Cardiff, CF24 3AA

Abstract

The machining response of amorphous and polycrystalline Ni-based alloys (Ni78B14Si8) to micro-second and pico-second laser processing was investigated. The shape and topography of craters created with single pulses as a function of laser energy together with holes drilled in both materials were studied. The carried out FIB analysis of craters in amorphous and polycrystalline samples revealed that processing both with micro-second and pico-second lasers does not lead to materials crystallization and the short-range atomic ordering of metallic glasses can be retained. When processing the amorphous sample the material laser interactions resulted in a significant ejection of molten material from the bulk that was then followed by its partial re-deposition around the craters. Additionally, there were no signs of crack formation that indicate a higher surface integrity after laser machining. A conclusion is made that laser processing both with short and long pulses is a promising technique for micromachining metallic glasses because does not lead to material crystallisation.

Process characterisation including process chains

A study of factors affecting the performance of micro square endmills in milling of hardened tool steels

P. Li (a), P. Aristimuno (b), P. Arrazola (b), A.M. Hoogstrate (c), J.A.J. Oosterling (c), H.H. Langen (a), R.H. Munnig Schmidt (a) (a) Department of Precision and Microsystems Engineering, Delft University of Technology, Delft, the Netherlands (b) Manufacturing Department, Faculty of Engineering, Mondragon University, Spain (c) APPE Precision Manufacturing, TNO Science and Industry, Eindhoven, the Netherlands

Abstract

Proper setting of cutting conditions is critical for the performance of micro endmills in micro milling of hardened tool steels. In this paper, the influence of the cutting parameters on the wear behaviour of micro square endmills is presented. The selected parameters are cutting speed, depth of cut, and feed per tooth; Central Composite experimental Design (CCD) was used for a statistical analysis of the influence of these parameters. A quadratic model was fitted to describe the performance of the tool wear; the ANOVA analysis shows that the quadratic model gives a good prediction of the experimental results. On considering the magnitudes of the coefficients it is seen that the feed per tooth has a greater influence on the tool wear than cutting speed and depth of cut within the tested process window. By applying this method, the micromilling process can be planned to achieve an optimum tool wear performance for a tool-workpiece combination.

Electrochemical finishing of nickel microstructures

S. Kissling, K. Bade Forschungszentrum Karlsruhe, Institut für Mikrostrukturtechnik, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

Abstract

One method to manufacture high aspect ratio metallic microstructures is the LIGA technique. The acronym LIGA stands for the German words for lithography, electroforming and moulding. A resist layer (e.g. PMMA) is structured using deep X-ray lithography. The resist is developed and the resulting mould is filled with metal by electroplating. Though electroplating is an essential part of the LIGA process there are still challenges concerning the deposit surfaces. Nevertheless, extremely precise metal structures can be manufactured. In particular, the sidewall surface quality can be in the sub-micrometer range. But due to irregularities during the deposition process, resulting in rough or wavy surfaces, the emerging surface does not meet required tolerances. For this reason, a finishing process is necessary. Electrochemical techniques such as electro- or plasmapolishing have been evaluated. Electropolishing, a common anodic dissolution technique widely used in industry to obtain smooth, bright and burr-free surfaces, as well as plasmapolishing, also a technique based on the anodic dissolution are presented. First results of both an electropolished and a plasmapolished nickel microstructure are reported.

Force analysis in micro milling Al 6082 T6 in various engagement conditions

G. Bissacco (a), T. Gietzelt (b), H.N. Hansen (c) (a) Department of Mechanics and Innovation (DIMEG), University of Padova, via Venezia 1, 35131Padova, Italy (b) Forschungszentrum Karlsruhe Institut für Mikroverfahrenstechnik, 76021 Karlsruhe, Germany (c) Department of Mechanical Engineering (MEK), Technical University of Denmark (DTU), Produktionstorvet 2800 Kgs. Lyngby, Denmark

Abstract

This paper discusses the issues related to force measurement in micro milling and presents the results of the experimental investigation performed in an on going Cross Divisional Project within the 4M network of Excellence, aiming at force analysis and process characterization in micro milling. Reliable force measurement in micro milling is shown to be a challenging task. Measured forces are affected by contributions coming from the machining system. Based on the performed measurements, tool engagement has been demonstrated to occur at each tooth passing, even at feeds per tooth as low as 2 μm.

Hot embossing of high aspect ratio sub-μm structured surfaces for micro fluidic applications

M. Heckele (a), M. Worgull (a), T. Mappes (b), G. Tosello (c), T. Metz (d), J. Gavillet (e), P. Koltay (d), H. N. Hansen (c) (a) Forschungszentrum Karlsruhe (FZK), Institute for Microstructure Technology (IMT), D-76344 Eggenstein-Leopoldshafen, Germany (b) University of Karlsruhe (TH), Institute for Microstructure Technology (IMT), D-76344 Eggenstein-Leopoldshafen, Germany (c) Technical University of Denmark (DTU), Department of Mechanical Engineering, DK-2800 Kgs. Lyngby, Denmark (d) Laboratory for MEMS Applications, Department of Microsystems Engineering (IMTEK), University of Freiburg, George-Koehler-Allee 103,79110 Freiburg, Germany (e) French Atomic Energy Commission (CEA), Laboratory of Innovation for New Energy Technologies and Nanomaterials (LITEN), 38054 Grenoble, France

Abstract

Sub-micro structured surfaces allow modifying the behaviour of polymer films or components. Especially in micro fluidics a lotus-like characteristic is requested for many applications. Structure details with a high aspect ratio are necessary to decouple the bottom and the top of the functional layer. Unlike to stochastic methods patterning with a LIGA-mould insert it is possible to structure surfaces very uniformly or even with controlled variations (e.g. with gradients). In this paper the process chain to realize polymer sub-micro structures with minimum lateral feature size of 400 nm and up to 4 μm height is presented.

Improved bonding strength in hybrid micro parts by using plasma

W. Michaeli, T. Kamps Institute of Plastics Processing at RWTH Aachen University, 52056 Aachen, Germany

Abstract

Micro injection moulding is established as one of the most common manufacturing processes for thermoplastic polymers due to its high degree of automation and the short cycle times. With micro assembly injection moulding, offline joining process steps can be avoided by overmoulding components of the micro system directly in the injection mould. Overmoulding can be used to generate movable or fixed combinations of different materials. One of the materials combined in a hybrid micro system is thermoplastic polymers, whereas the other one can be selected from a wide range of materials, e.g. technical ceramics, glass, or metals. Micro assembly injection moulding provides several advantages compared to other joining processes. However, functional integrity of the micro system is an end requirement. In the case of a joint micro structure, the bonding strength between two components affects the stability of the whole micro system and is thus important for the part’s quality. As tests conducted at IKV show, a plasma treatment (plasma activation) of the insert parts significantly increases the bonding strength. Inserts of metal and glass have been overmoulded with several polymers, and the influence of different plasma gases and duration of the treatment on the feasible bonding strength is shown.

Influence of process parameter variation on ceramic feedstock flow behaviour

T. Hanemann (a), (b), and J. Aroni (a) (a) Forschungszentrum Karlsruhe, Institut f. Materialforschung III, D-76021 Karlsruhe, Germany (b) Albert-Ludwigs-Universität Freiburg, Institut f. Mikrosystemtechnik (IMTEK), D-79110 Freiburg, Germany

Abstract

With respect to feedstock development for different ceramic injection molding techniques the influence of various process parameters during feedstock development was investigated systematically. First the dispersant concentration at the fillers surface was changed in a wide range. The impact on the particle size distribution was measured. Second the size and the geometry of the used stirrers for compounding in an unsaturated polyester resin as polymer matrix were varied. The resulting composite flow properties at a fixed solid load and different temperatures were determined experimentally using a cone and plate rheometer. Increasing dispersant amounts at the alumina surface lead to a change of the particle size distribution and to a significant composite viscosity drop. The use of different stirrers affects directly the composite viscosity as well as the flow behaviour to a certain extent.

Investigations in Variothermal Injection Moulding of Microstructures and Microstructured Surfaces

W. Michaeli (a), F. Klaiber (a), S. Scholz (b) (a) Institute of Plastics Processing, RWTH Aachen University, Aachen, Germany (b) The Manufacturing Engineering Centre, Cardiff University, Cardiff, CF24 3AA, UK

Abstract

Telecommunication, information and medical industries have a high growth potential. A key technology for those industries is the replication of microstructures. Precise microstructured parts with functional surfaces can be produced economically by injection moulding. The whole process chain (thermal mould condition, moulding, demoulding, measurement and analysis) must be analysed carefully to ensure the highest precision and reliability. To enable the precise production of such structures fundamental studies were conducted at the Institute of Plastics Processing (IKV). The studies considered several polymers (PMMA, POM) on the one side and various test structures on the other side. In addition an innovative external inductive heating unit was analysed and implemented into the process to heat the cavity surface efficiently. Using this technique cavity surface temperature increase rates of up to 60 K/s have been achieved. A pyrometer was implemented for contact less instant temperature measurement, and controller was used to realise preset cavity temperatures by regulating the inductor power. With the dynamic inductive heating system the moulding accuracy of the microstructures could be increased drastically. The final step of the process chain comprises of the measurement and analysis of the microstructured moulded parts. To analyse the microscopic deviation between the mould cavity and the surface of the moulded part scanning electron microscopy (SEM) and white light interferometry (WLI) was used.

Manufacturing and verification of tools for ECF

K. Hofmann (a), L. Staemmler (b), H. Kück (a), (c) (a) Institute of Micro- and Precision Engineering (IZFM), University of Stuttgart, 70569 Stuttgart, Germany (b) now: Greiner Bio-One GmbH, 72636 Frickenhausen, Germany (c) Hahn-Schickard-Institute for Micro Assembly Technology (HSG-IMAT), 70569 Stuttgart, Germany

Abstract

The electrochemical milling with ultra short voltage pulses (ECF) displays an important progress in micromachining of hard materials. Machining a workpiece with conventional milling the removal takes place by shape cutting. Therefore mechanical forces are applied to tool and workpiece. In contrast, using electrochemical milling, the material removal occurs by an electrochemical reaction. Therefore the workpiece as well as the tool are submerged into an electrolyte and the surface of the workpiece is etched by a galvanic current. Hereby the so called working distance is formed between tool and workpiece, which goes linear with the pulse amplitude and pulse on time in a first approximation. As a result, there are no mechanical forces applied to the tool. This allows the use of very thin tools. To achieve the highest precision with this technique, it is necessary to manufacture very precise tools and to verify their shape and dimensions. In addition the use of rotating tools could be a promising strategy to speed up the ECF process and reduce the roughness. Therefore we introduce a method to produce very thin rotation-symmetric tools with high precision using the ECF technique. While the tool rotates the diameter is reduced by a one sided removal of material similar to machining with a turning lathe. To verify the shape and the dimensions of these tools a commercial laser measuring system for tool setting and breakage control was integrated into the ECF machine. Algorithms to determine the tool diameter and the toolshape are installed. Further algorithms have to be developed to characterize more details of the tool like tilt and run-out error.

Micro injection moulding: an experimental study on the relationship between the filling of micro parts and runner designs

C.A. Griffiths, S.S. Dimov, E.B. Brousseau Manufacturing Engineering Centre, Cardiff University, CF24 3AA, UK

Abstract

To increase productivity and thus reduce the unit cost, often micro moulding tools incorporate multiple cavities. For this a runner design must be selected, the main function of the runner system is to facilitate the flow of molten material from the injection nozzle into the mould cavity. Therefore, the micro injection filling process depends on the optimum design of runner systems. In this context, the paper reports an experimental study that investigates the flow behaviour of the polymer melts in micro cavities with a particular focus on the relationship between the filling of micro parts and the size of the runner system. In particular, the runner size effects on the micro injection moulding process were investigated. The filling performance of spiral-like micro cavities was studied as a function of runner size in combination with melt temperature, mould temperature, injection speed and holding pressure time employing the design of experiment approach. In addition, the results were analysed further to identify the effects of the runner size together with flow properties of polymers, PP and ABS, on the behaviour of the micro injection moulding process.

Micro-Injection moulding: surface treatment effects on part demoulding

C.A. Griffiths (1), S. S. Dimov (1), E.B. Brousseau (1), C. Chouquet (2), J. Gavillet (2), S. Bigot (1) (1) Manufacturing Engineering Centre, Cardiff University, Cardiff CF24 3AA, UK (2) French Atomic Energy Commission (CEA), Laboratory of Innovation for New Energy Technologies and Nanomaterials (LITEN), 38054 Grenoble, France

Abstract

Micro injection moulding as a replication method is one of the key technologies for micro manufacture. The understanding of process constraints for a selected production route is essential at both the design stage and during mass production. In this research a tool surface treatment is used to study the effects of demoulding a part with micro features. In particular a tool coated with diamond like carbon (DLC) will be compared to an identical tool without coating. Through a range of experimental trials the effects of four process parameters, namely melt and mould temperature, and cooling and ejection time will be used to evaluate the demoulding process. Using two polymer materials PP and ABS, a special attention is paid to the forces present in demoulding and conclusions are made about the influence of DLC surface treatments and the factors affecting demoulding.

Strategies for material removal in laser milling

P V Petkov, S Scholz and S Dimov Manufacturing Engineering Centre, Cardiff University, Queen's Buildings, The Parade, Newport Road, Cardiff, CF24 3AA, UK

Abstract

Laser milling with microsecond pulses is a thermal material removal process usually associated with detrimental effects such as heat affected zones (HAZ), a recast layer and debris. Process optimisation can lead to considerable reduction of the above mentioned negative effects. In this context, the research investigates the effects of tool path optimisation and material removal strategies on the resultant surface quality and edge definition. The conducted experimental study shows clearly that the applied milling strategies have a significant effect on the resulting surface topography and the edge definition. Also, the research demonstrates that by optimising the laser path and material removal strategies it is possible to reduce significantly the thermal load when milling micro features, and thus to minimise HAZ and other secondary effects.

TEM/SEM and FT-IR characterization of biocompatible magnetic nanoparticles

K. Alexandrova (a), I. Markov (a) – Deneva (b), A. Gigova (a), I. Dragieva (a) (a) Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, Sofia, Bulgaria, (b) University of Chemical Technology and Metallurgy, 1756 Sofia, 8 Kl. Ohridski Blvd., Bulgaria,

Abstract

Fe-Co-Cr-B(N,C,O,H) nanoparticles were synthesized by chemical reduction in aqueous solutions of cobalt precursor complexes such as (ethylenediamine)dichloro cobalt chloride [Co(en)2.Cl2]Cl and aqua solutions of FeCl2.4H2O and CrCl3.6H2O with sodium borohydride as reducing agent. During the synthesis a reactor insuring hydrodynamic conditions of ideal mixing for solutions at a room temperature and atmospheric pressure was used. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transformation infra red spectroscopy (FT-IR) investigations of nanoparticles obtained were carried out. The influence of the applied d. c. magnetic field during the synthesis on their properties were established. It is visible that a d. c. magnetic field induces a chain arrangement of nanoparticles with higher hydroxide content, possessing higher coercive force and lower transmittance determined by FT-IR.

Template fabrication incorporating different length scale features

G. Lalev (1), P. Petkov (1), N. Sykes (2), V. Velkova (1), S. Dimov (1), D. Barrow (2) (1) Manufacturing Engineering Centre, Cardiff University, Newport Road,Cardiff, CF24 3AA, UK (2) metaFAB, Cardiff University, Newport Road, Cardiff, CF24 3AA, UK

Abstract

A cost effective methodology for pattering of Nano Imprint Lithography (NIL) templates with different length scale features is proposed. The approach relies on selecting the optimum processing window of different technologies for cost effective micro and nano patterning. Very promising results were obtained when first fused silica templates were structured by F2 laser ablation at 157 nm without inducing phase transformation of the material. It was demonstrated that nanoscale features and complex 3D microscale features could be machined with a Focused Ion Beam (FIB) over the existing topography produced by laser ablation. Thus, a large area (up to several square centimetres) of the NIL templates is easily patterned with micro- and even meso-scale features by laser ablation while nano- and micro-scale features could be introduced by FIB machining.

Wire electro discharge grinding: surface finish optimisation

A. Rees (a), E. Brousseau (a), S.S. Dimov (a), H. Gruber (b), I. Paganetti (b) (a) Manufacturing Engineering Centre, Cardiff University, CF24 3AA, UK (b) AGIE AG für Industrielle Elektronik, Losone, Switzerland

Abstract

This paper investigates the technological capabilities of a micro machining process for performing Wire Electro Discharge Grinding (WEDG). In particular, micro Wire Electrical Discharge Machining (μWEDM) is employed in combination with a rotating submergible spindle to perform WEDG. In this paper, the effects of different factors on the achievable surface finish after WEDG are investigated. In particular, an experimental study employing the Taguchi parameter design method is conducted to identify the most important main cut machining parameters that affect the surface quality of the machined parts. Then, the obtained results are used to analyse the effects of the investigated parameters on the achievable surface roughness, and ultimately to select the optimum technological parameters for performing WEDG. The process parameters that statistically have a significant influence on the surface finish are presented. The study shows that by optimising the main cut machining parameters of WEDG a level of surface finish comparable to that of μWEDM can be achieved.

Process modelling and simulation 

Geometry Optimization of Micro Milling Tools

J. Fleischer, M. Deuchert, C. Kühlewein, C. Ruhs Institute of Production Science (wbk), Universität Karlsruhe (TH), Kaiserstrasse 12, 76131 Karlsruhe, Germany

Abstract

The geometry of micro milling tools currently in use have been adopted from macro tools, assuming that chip formation and process kinematics are analogical in both types of tools [1]. Experience has proved that micro tools respond to influences in a very different way than macro tools [2]. Oftentimes, structural details such as the rake angle and the twist angle impede further miniaturization and are impossible to achieve with conventional manufacturing techniques. Therefore it is necessary to get a comprehensive understanding of the entire process by taking a structure mechanical and cutting technological approach to micro milling tools in order to be able to optimize them. Another objective consists in the production of these miniaturized milling tools by means of force-free procedures such as laser ablation and electrical discharge machining. The present state of research already puts the deficits of the currently available tools on display. Insufficient manufacturing tolerances of ±10 μm, constitute a substantial change of cutting conditions for the commonly used lateral infeed or feed per tooth of a few micrometers. Sometimes, only one cutting edge is engaged, which results in increased wear and, therefore, reduced durability, increased cutting forces, minor surface quality and a higher probability of milling cutter breakage. For that reason, a single-edged geometry has been proposed. It guarantees clear adjustment of the process parameters feed per edge and lateral infeed. For that purpose, stability analyses of simple stylus geometries have been conducted by means of FEM simulations. The resulting tool with a diameter down to 30 μm was machined on the EDM-machine at the wbk (Sarix SX 100). First tests have been carried out that prove the ability of these tools to cut steel.

Implementation strategies for the optimization of micro injection moulding simulations

G. Tosello (a), A. Schoth (b), H.N. Hansen (a) (a) Technical University of Denmark (DTU), Department of Mechanical Engineering, Produktionstorvet, Building 427S, DK-2800 Kgs. Lyngby, Denmark (b) Laboratory for Process Technology, Department of Microsystems Engineering (IMTEK), University of Freiburg, George-Koehler-Allee 103,79110 Freiburg, Germany

Abstract

In polymer micro manufacturing technology, software simulation tools adapted from conventional injection moulding can provide useful assistance for the optimization of moulding tools, mould inserts, micro component design, and process parameters. Conventional implementation methods of simulation are not suitable for micro injection (μIM) application and are limiting the possibility to extend the use of existing packages for the modelling and the simulation of polymer micro parts. Different strategies optimized for the set-up the simulation of a miniaturized part with micro features are presented. Model design and mesh issues are discussed, as well as dynamic implementation of the flow constrains for the creation of an effective interface between the machine and the polymer flow in the simulation software. The results of the different methods are evaluated by means of a quantitative study which compares the simulated results and the actual micro injection moulding experiments.

Influence of Force Components on Thin Wire EDM

A. Herrero (a), S. Azcarate (a), A. Rees (b), A. Gehringer (c), A. Schoth (c), J.A. Sanchez (d) (a) Micro & Nano Technologies Dep., Fundacion Tekniker, Avda. Otaola 20, 20600 Eibar, Spain (b) Manufacturing Engineering Centre, Cardiff University, Cardiff, CF24 3AA, UK (c) IMTEK, University of Freiburg, Georges-Koehler Allee 103, EG-79110, Freiburg, Germany (d) Dep. of Mechanical Engineering – Faculty of Engineering of Bilbao, Avda. Urquijo s/n, 48013 Bilbao, Spain

Abstract

Apart from the important role that Micromachining and Ultraprecision machining has provided to the development of improved or innovative miniaturised products, these techniques have also attracted the interest of the researchers to obtain the highest accuracy and a thorough analysis of the principles governing the material removing mechanisms. The present article exposes the theoretical analysis of some aspects of the thin WEDM that drop the process accuracy in terms of minimum machinable slot or corner over/undercutting. The scaled electrode dimensions and the reduced power supply with respect to the normal process causes a different influence of the process variables and contributes to obtain complementary information about the WEDM process. The different force components contributing to the wire deformation are discussed and some of them are analyzed from a theoretical point of view presenting analytical calculations to evaluate their expected magnitude and pointing out the difficulties to obtain an experimental characterisation of each phenomena.

Micro injection moulding: simulation of melt flow behaviour

C.A. Griffiths, S.S. Dimov, E. B. Brousseau and M. S. Packianather Manufacturing Engineering Centre, Cardiff University, Cardiff CF24 3AA, UK

Abstract

Micro injection moulding as a replication method is one of the key technologies for micro manufacture. The understanding of process constraints for a selected production route is essential at both the design stage and during mass production. In this research, an existing Finite Element Analysis (FEA) system is used to study the effects of four process parameters, namely melt and mould temperature, injection speed and part thickness. A special attention is paid to the melt flow sensitivity when filling micro channels, particularly the factors affecting shear rate and flow front temperature. The results obtained from two different simulation models are presented for two polymer materials, PP and ABS and conclusions are made about the important factors affecting part quality.

Modelling the Solidification-Structure of Al Micro-Castings as a function of their Aspect Ratio and Mould Pouring Temperature

J-F. Charmeux (a), R. Minev (a), S. Dimov (a), E. Minev (a) (a)Manufacturing Engineering Center, Cardiff University, Cardiff, CF24 3AA, UK

Abstract

Producing micro-castings trough vacuum investment casting is known to be associated with high cooling rates due to small scale of the castings. High cooling rates together with alloy composition might be the main factors affecting the final metallographic structure of castings’ alloys during the solidification process. When using Al-Si-Mg casting alloys, the size of the dendritic structure can be used for a non-destructive test to assess the mechanical properties and overall quality of the castings. Also the ability of the alloys to be structured by different mechanical and energy assisted processes is highly dependant on their metallographic structure. Based on earlier experimental results, this paper proposes an empirical model describing the degree of dendrite cell refinement in cast microfeatures as a function of their AR and mould pouring temperature. Additionally, the paper reports the strong correlation between the DCS refinement and the changes in the mechanical properties of the castings through MHV measurements following a Hall-Petch equation type.

Numerical modelling and experimental characterization of short pulse laser microforming of thin metal sheets

J.L. Ocaña, M. Morales, C. Molpeceres, O. García, J.A. Porro, J.J. García-Ballesteros Centro Láser UPM. Ctra. de Valencia, km. 7,3. 28031 Madrid. Spain

Abstract

Continuous and long-pulse lasers have been extensively used for the forming of metal sheets for macroscopic mechanical applications. However, for the manufacturing of micro-mechanical systems (MMS), the applicability of such type of lasers is limited by the long relaxation time of the thermal fields responsible for the forming phenomena. As a consequence, the final sheet deformation state is attained only after a certain time, what makes the generated internal residual stress fields more dependent on ambient conditions and might difficult the subsequent assembly process. The use of short pulse (ns) lasers provides a suitable parameter matching for the laser forming of an important range of sheet components used in MMS. The short interaction time scale required for the predominantly mechanic (shock) induction of deformation residual stresses allows the successful processing of components in a medium range of miniaturization (particularly important according to its frequent use in such systems). In the present paper, a discussion is presented on the specific features of laser interaction in the timescale and intensity range needed for thin sheet micro-forming with ns-pulse lasers along with relevant modelling and experimental results and a primary delimitation of the parametric space of the considered class of lasers for the referred processes.

On the force between two metallic plates of a gripper immersed in a nonpolar fluid

D. Dantchev, K. Kostadinov Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev St. Bl. 4, 1113 Sofia, Bulgaria

Abstract

We analyse, as a function on the temperature T and the chemical potentialμ , the total force ( , , ) tot F Tμ L between two metallic plates of a gripper separated at a distance L from each other and immersed in a nonpolar fluid which can be liquid, or gas. In our approach we take into account the direct substrate-substrate van der Waals interaction, the van der Waals interactions between the molecules of the fluid with the other molecules of the fluid as well as with the constituent elements of the substrate, and the interaction between the plates generated by the fluctuations of the density of the fluid (i.e., the Casimir force). We suppose that both plates are equal and strongly prefer the liquid phase of the fluid. Under such boundary conditions both the direct plate-plate van der Waals interaction, as well as the Casimir force, are forces of attraction of the plates toward each other. In the phase space (temperature, chemical potential), we identify the regions where the net interaction force is the strongest. It turns out that these regions are close to the bulk critical point of the fluid ( = ,μ=μ) c c T T , and near the so-called capillary condensation regime < ,( / )(Δμ / ) = (1) c B T T L a kT O , with Δμ=μ−μ <0 c and a the characteristic distance between the molecules of the fluid. These regions shall be avoided in order to prevent sticking of the plates of the gripper on each other.

Simulation of Microforming Processes by Applying a Mesoscopic Model

S. Geißdörfer (a), U. Engel (a), M. Geiger (a) (a) Chair of Manufacturing Technology, University of Erlangen-Nuremberg, Egerlandstrasse 11, 91058 Erlangen

Abstract

Continued miniaturization in many fields of forming technology implies the need for a better understanding of the effects occurring while scaling down from conventional macroscopic scale to microscale. At microscale, the material can no longer be regarded as a homogeneous continuum because of the presence of only a few grains in the deformation zone. This leads to a change in the material behaviour resulting among others in a large scatter of forming results. A correlation between the integral flow stress of the workpiece and the scatter of the process factors on the one hand and the mean grain size and its standard deviation on the other hand has been observed in experiments. Conventional FE-simulation, is not able to consider the size-effects observed when scaling down processes. Actually the reduction of the flow stress the increasing scatter of the process factors and a local material flow being different to that obtained in the case of macroparts. For that reason, a new simulation model has been developed taking into account the size-effects. The present paper deals with the theoretical background of the new mesoscopic model, its characteristics like synthetic grain structure generation and the calculation of micro material properties - based on conventional material properties. The verification of the simulation model is done by carrying out various experiments with different mean grain sizes and grain structures but the same geometrical dimensions of the workpiece.

А study of the gate size effects on the process of optical data storage micro-scale replication

D. S. Trifonov (a), Y.E. Toshev (b) (a) Institute of information Technology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria (b) Institute of Mechanics and Biomechanics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Abstract

The present paper offers 3D CAD models of the gate system of an optical disc mould that are developed. The type of the gate system is known as a “Krauss Maffei” system, in which the central hole of the polymer substrate is formed by breaking off the circle gate from the polymer substrate. The gate depth and the gate position are defined as variable parameters and combined with different variants of the processing conditions in mould filling simulation. A range of improved variants of all the variable parameters is obtained with the help of iterative steps within the frame of the simulation code. A modified gate system is proposed in the process of research, which allows a gate with a larger depth parameter to be used. The modified system allows also alteration of the gate position with respect to the central hole. The best results are achieved, using the proposed modified gate system in the case, when a gate with a larger depth is used and the gate position is located symmetrically towards the central hole.

Systems: novel product and system designs 

Active microvalves for micro-fluidic networks in plastics – selecting suitable actuation schemes

A.Boustheen (a), F.G.A. Homburg (a), J.E. Bullema (b), A. Dietzel (a), (c) (a) Micro and Nano Scale Engineering, Eindhoven University of Technology, The Netherlands (b) TNO Science and Industry, Eindhoven, The Netherlands (c) Holst Center, Eindhoven, The Netherlands

Abstract

Using active microvalves liquid flow in microsystems can be precisely controlled and timed. Plastic microfluidic networks offer high flexibility in the material selection and potentially also allow for low cost mass fabrication. For selecting a suitable micro-actuation scheme, the different options are compared on the basis of actuation performance parameters. For thermal-expansion, electrostatic, electroactive, piezoelectric and shape memory actuation principles the work density is derived from basic actuator physics and literature material parameters. For the targeted actuator dimensions also frequency, stroke and force characteristics are calculated. These are compared with actuator performance targets typical for micro-fluidic networks: forces between 160μN and 16mN, stroke of 50μm, repetition frequencies ranging from 100Hz to few mHz. As a result, only electroactive polymer and thermal actuation principles remain as viable options and shall in further work be experimentally evaluated using a modular design with interchangeable actuators.

An integrated all-optical microfluidic particle sorter

S. Valkai, H. I. Kirei, L. Oroszi and P. Ormos Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, H-6726 Szeged, Hungary

Abstract

A fully integrated microfluidic sorter is introduced. It is able to count, characterize and sort micrometer sized articles and cells. All functions of the device are performed by light. The objects to be sorted are counted optically, they are characterized by measuring their fluorescence. Even the sorting itself, directing the particles into different channels is performed by the pressure of light. The device is built by photopolymerization, from a light cured optically clear resin upon a glass plate support. The whole structure is created in a single photolithography step. The microfluidic channels and optical waveguides that carry the illuminating, detecting and sorting light form a single integrated structure. The supporting units, like sample reservoirs, pumps, light sources, light detectors are easily connected to the device from the outside. The device is optimized for simplicity. It is a proof-of-concept instrument, it demonstrates that it is possible to build simple optically driven microfluidic systems that perform complicated functions.

Feasibility of polymers for wafer scale capping of RF MEMS

P.J. Bolt, J.E. Bullema, R. Korbee, R. Kusters TNO Science and Industry, Eindhoven, The Netherlands

Abstract

This paper concerns the feasibility of polymer capping of RF-MEMS devices, replacing traditional silicon solutions. The advantage would be less costs and potential for both further miniaturisation and integration of electrical functions in the cap. One of the challenges is the resistance against expoxy overmoulding as part of the traditional back-end process chain. This involves temperatures of 175oC and pressures of 10MPa, which the cap has to withstand. Calculations are made and experiments carried out to investigate the feasibility of selected polymers. It is shown that nanofillers will lift the polymers mechanical properties comfortably above the minimum established demands.

Low-power humidity sensor for RFID applications

L. Löfgren (a), B. Löfving (a), T. Pettersson (a), B. Ottosson (a), C. Rusu (a), S. Haasl (a), K. Persson (a), O. Vermesan (b), N. Pesonen (c), P. Enoksson (d) (a) The Imego Institute, Arvid Hedvalls Backe 4, SE-400 14 Göteborg, Sweden (b) SINTEF ICT, N-0314 Oslo, Norway (c) VTT, Wireless sensors, FIN-02044, Espoo, Finland (d) Chalmers University of Technology, Micro and Nanosystems group, SE-41296 Göteborg, Sweden

Abstract

Wireless sensors incorporated in RFID systems are important in several industrial, consumer and logistics applications. By extending RFID tags to sensing applications, the products become smarter. Application areas for these smart tags include; health care (verification of the environmental conditions during transport or in storage of e.g. diapers, bandages, etc.), food monitoring (food quality during transport, storage and sales) and construction industry (e.g. building material). In this paper, a small, very low power and low cost humidity sensor tailor made for passive RFID applications is presented. The sensor consists of a glass chip substrate with a sub-micron interdigitated gold electrode structure covered with a humidity sensitive polyimide layer. The humidity absorbed by the sensing layer is measured capacitively. Finite element modeling and analytic calculations were used to determine the design of the interdigitated electrodes and the optimal thickness of the polyimide layer. A read-out electronics circuit was designed and used to evaluate the sensor. Sensors were fabricated and calibrations have been made to verify their function. The sensor response was close to linear from below 20 to above 90 %RH and its response time was proven to be at least as short as that of the climate chamber, namely 0.1 %RH/s. The concept can easily be adapted to measure a range of other parameters such as temperature or the presence of certain substances.

Sub-Micron Referencing System for Ultraprecision Machining Processes

C. Brecher (a), (c), M. Weinzierl (a), A. Rashid (b), R. Schmitt (c), D. Köllmann (c) (a) Fraunhofer Institute for Production Technology IPT, Germany (b) System 3R Intl. AB, Sweden (c) Werkzeugmaschinenlabor (WZL), RWTH Aachen University, Germany

Abstract

The set-up of ultraprecision machining processes is characterized by manual process steps which require a lot of personal skill and experience to full fill sub-micron requirements in form accuracy. Besides the fact that these manual process steps require a lot of time, they individualize each ultraprecision machined work piece and therefore prevent ultraprecision machining processes from becoming universal and cost efficient machining processes for high precision work pieces. To overcome this deficit, automation solutions are developed within the European Integrated Project (IP) »Production4μ« which enable the realization of efficient ultraprecision process chains with a high level of accuracy. In this paper, a sub-micron referencing system is introduced, which has been developed within this IP to contribute to the high accuracy process chains by enabling the automated and repeatable clamping of work pieces with submicrometer deviations from their original position. This does not only enable the efficient combination of different machine-tools and processes but also allows for an increase in product quality.