Components: Fabrication and Assembly Technologies

Replication of micrometric pattern by hot embossing of silica based feedstock

L. Federzoni a, O. Fourcade a , P. Lourdin b
a CEA-Grenoble, DTNM//LCE, F38054 Grenoble cedex 9
b ECAM, 40 montée saint Barthélémy F69321 Lyon cedex

Abstract

The CEA is developing a new forming technique derived from the hot embossing of polymers. This technique consists in replacing the polymer by a feedstock composed on binders and inorganic nanopowders. The process consists in three stages that are forming/pressing, debinding and sintering, similarly to the micro Powder Injection molding. This process has been optimized for the replications of micrometric patterns. This work has led to the development of a feedstock composed of water-soluble binder and nanometric fumed silica. It was possible to replicate gratings of ~1 micron after sintering. The replication of sub-micronic plots is not possible at this stage. It is expected that the use of smaller particle size could allow reaching this objective.

Keywords: hot embossing, gratings, silica

Force fields with one stable equilibrium for micropart 2D manipulation

E.K. Xidias a, N.A. Aspragathos a
a Department of Mechanical Engineering & Aeronautics, University of Patras, Patras 26500, Greece

Abstract

This paper proposes an approach for structuring a two dimensional (2D) force field with just one stable equilibrium at the desired location for the manipulation of microparts without sensing. The derived force field induces a unique stable equilibrium for any convex or non-convex polygonal micropart on the plane with arbitrary shape and size, where the equilibrium pose is the desired location of the micropart. Extensive simulations show the efficiency of the proposed method in the formulation of the force fields for 2D manipulation of microparts.

Keywords: stable equilibrium, force field, micropart manipulation

Off-Axis Machining of NURBS Freeform Surfaces by Fast Tool Servo Systems

Prof. Dr.-Ing. C. Brecher, Dr. S. Lange, M. Merz, F. Niehaus, M. Winterschladen
Fraunhofer Institute for Production Technology IPT,
Steinbachstraße 17, 52074 Aachen,Germany

Abstract

The manufacturing of optical components with complex geometries like freeform surfaces is getting more and more important. Mass production of these optics is enabled by replication methods like injection moulding. For the machining of the required mould inserts with freeform geometries ultraprecision technologies like Fast Tool Servo turning can be applied to achieve the appropriate optical surface quality. For the mathematical description of freeform surfaces NURBS (Non Uniform Rational Basis Splines) are highly applicable. To avoid interpolation errors and to create set points with a continuous and smooth path of motion a trajectory generator directly based on NURBS data has been developed for Fast Tool Servo assisted turning [1], which evaluates the NURBS surface in each position control cycle. An approach of increasing the efficiency of manufacturing freeform surfaces is the off-axis machining of multiple workpieces at the same time. The paper presents the different process steps in simulation and off-axis machining of freeform surfaces using Fast Tool Servo assisted turning in conjunction with NURBS based data processing.

Keywords: Ultraprecision Machining, Fast Tool Servo System, Freeform Surfaces (NURBS), Off-Axis Turning

Automated tool exchange for ultraprecision diamond milling and turning applications

Prof. Dr.-Ing. Christian Brecher, Dr.-Ing. Sven C. Lange, Frank Niehaus, Christian Wenzel
Fraunhofer-Institute for Production Technology IPT,
Steinbachstrasse 17, 52074 Aachen, Germany

Abstract

Active tool wear control is a crucial factor for fulfilling the high shape and surface requirements in the large area ultraprecision diamond surface structuring of optical components. The Fraunhofer IPT has developed opto-mechanical setups for a fully automated in situ tool characterisation and a reproducible tool exchange. The systems embody a submicron accuracy for both, the machining of planar masters for replication by means of planing and fly-cutting operation as well as for the turning of large rollers for embossing applications.

Keywords: diamond turning, ultra-precision machines, automated referencing and tool exchange, tool wear control

Polymer Based Multifunctional 3D-Packages for Microsystems

W. Eberhardt a, D. Ahrendt a, U. Keßler a, D. Warkentin a, H. Kück b
a Hahn-Schickard-Institute for Microassembly Technology HSG-IMAT, Stuttgart, Germany
b University of Stuttgart, Institute for Micro and Precision Engineering, Germany

Abstract

Multifunctional 3D-packages can be fabricated with nearly any geometry using injection moulding. 3D line patterning can be performed on injection moulded parts with very flexible laser techniques. Finest line pitches can be realized with subtractive patterning as well as with additive laser direct structuring (LDS). For mounting of SMD and bare dies different assembly techniques can be used.

Keywords: MID, laser patterning, assembly, bare die, SMD

Laser transmission welding of micro plastics parts

E. Haberstroh, W.-M. Hoffmann
Institute of Plastics Processing (IKV), RWTH Aachen University, Aachen, Germany

Abstract

Only few welding processes for plastics meet the special demands of microtechnology. Laser transmission welding has distinctive advantages like low mechanical and thermal load of the joining parts. Thus the laser is a joining tool which is particularly suitable for the welding of micro plastics parts. Contour welding is a process variant of laser transmission welding enabling the welding of complex and even three-dimensional weld contours. In addition to that, this is a very flexible process which can be easily adapted to changing part geometries. So far it is only applied for welding plastics parts of macroscopic scale in the industrial practice. Recent research at the Institute of Plastics Processing in Aachen shows that it is also possible to use this process to weld filigrane micro parts. Thus another promising welding process has proven its suitability for the microtechnology. Welding trials with different thermoplastics show, however, that there are big differences in the material behaviour that make some platics more suitable than others for the contour welding in microtechnology.

Keywords: laser transmission welding, contour welding, tear-out force, weld seam morphology

Prototyping of multilayer waveguides with V-grooves in COC/Topas®

F. Bundgaard a, J. Ducrée b, R. Zengerle c, O. Geschke a

a MIC - Department of Micro and Nanotechnology, Technical University of Denmark,
DTU Building 345 East, DK-2800 Kgs. Lyngby, Denmark

b HSG-IMIT, Institute for Micromachining and Information Technology,Villingen-Schwenningen, Germany

c IMTEK - University of Freiburg, Laboratory for MEMS Applications,
Georges-Köhler-Allee 106, 79110 Freiburg, Germany

Abstract

A number of fast and low-cost methods are used for prototyping of optical waveguides in the cyclic olefin copolymer Topas®. This polymer has a number of advantages compared to polymers traditionally used for micro systems. The advantages include good chemical resistance, good optical properties, and low water absorption, making it well-suited for lab-on-a-chip systems. Using micro milling, spin coating, and thermal bonding, and exploiting the different refractive indices of different grades of Topas®, waveguides with a width and heigth of 130 μm are created. 45° V-grooves at both ends of the waveguides are used for coupling light in and out of the waveguides, using the principle of total internal reflection. In this manner light can be coupled into the waveguides perpendicularly from above or below the structure, depending on the groove orientation. This coupling scheme has a large potential for rotating microfluidic system, the so-called lab-on-a-disk systems.

Keywords: COC/Topas®, micro milling, waveguides, prototyping, V-grooves

An integrated solenoid-type inductor with Fe-based soft magnetic core

Chong Lei a, Yong Zhou a, Wen Ding a, Xiao-Yu Gao a, Ying Cao a, Hyung Choi b,Jonghwa Won b
a National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and
Microfabrication of Ministry of Education, Institute of Micro and Nano Science & Technology, Shanghai Jiao Tong
University, Shanghai 200030, China (corresponding author: yzhou@sjtu.edu.cn)

b Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., 416 Maetan-Dong,
Yeongtong-Gu, Suwon, Kyungki-Do 442-742, Korea

Abstract

This paper reports on a technological process that combines copper as conductor, soft FeCuNbCrSiB magnetic thin film prepared by magnetron sputtering as magnetic core and polyimide as the insulation material to complete a solenoid-type inductor with high inductance and high quality factor. The shape of the magnetic core scheme is rectangular, and the size of the inductor is 4 mm × 4 mm × 0.084 mm. The results show that the fabricated solenoid-type inductor has high inductance and high quality factor in the frequency range of 1-20 MHz, the inductance is 1.19 μH at a frequency of 1 MHz and the maximum quality factor is around 4.5 with an
inductance value of 1.1 μH at a frequency of 12 MHz.

Keywords: high inductance, high quality factor, Fe-based magnetic thin film, solenoid-type inductor

In-process assembly of micro metal inserts in a polymer matrix

G. Tosello, H. N. Hansen

Department of Manufacturing Engineering and Management, Technical University of Denmark,
Produktionstorvet, Building 427S, DK-2800 Kgs. Lyngby, Denmark

Abstract

New functionalities and smaller dimensions of micro products can be achieved by means of a higher degree of integration of both materials and components. Smart micro assembly techniques (such as on-the-machine assembly) together with hybrid structures (as metal inserts in polymer matrix) are suitable solutions to manufacture new micro products with several integrated functionalities, reduced number of components and assembly phases, as well as the possibility to be replicated in a high number of specimens. Innovative manufacturing systems, as well as new design rules and testing methodologies, have to be established in order to be able to develop new and more integrated micro products. In this paper a method for testing the bonding between micro thickened metal inserts and the polymer matrix they are moulded in is presented. A specific demonstrator has been manufactured by means of a hot embossing-like process which allows fast developing time and the possibility of batch process. Different levels of surface roughness and metal insert thickness were applied in a systematic design of experiments. The results show a strong influence of surface texture on bonding strength. The testing procedure assists the designer in giving data to be used when dimensioning micro products involving integrated metal parts in a polymer product.

Keywords: bond strength testing, micro metal inserts, polymer hybrid structures, in-process assembly

Low Temperature Adhesive Bonding in MEMS

D. Andrijasevic a, W. Smetana a, D. Esinenco b, W. Brenners a
a Institute of Sensor and Actuator Systems, Vienna University of Technology, 1040 Vienna, AUT
b The National Institute for Research and Development in Microtechnologies, 077190 Bucharest, RO

Abstract

A new concept for adhesive bonding of components with dimensions less than 300 μm in complex 3D structures is presented in this paper. Two different kinds of adhesives - polyurethane adhesive foil and polyethylene hot melt glue - were applied to the basic substrate by different techniques. The focused stream of hot gas directed to the substrate softens glue which had been applied as a solid. Afterwards, micro-parts were embossed in the softened glue, or covered and shielded by it. After cooling down at room temperature, a rigid and compact bond was formed. The parameters which induce the heat transfer and the process performance generally are considered through various experiments. The advantages of this new approach are compact system which can be easily integrated in existing production lines, low capital costs, partial reversibility, applicability to many material combinations, localized heating with reduced thermal stresses, etc.

In order to confirm the advantages of proposed bonding technique, a single mode glass optical fiber (core diameter 9 μm; cladding diameter 125 μm) was positioned in V-grooves to achieve requested alignment and positioning precision. V- grooves were made by chemical etching of silicon in the “111” plane. Bonding glass to glass was also successfully demonstrated.

Keywords: adhesives, low temperature bonding, hot gas stream

Manufacture of recessed rotating microelectrodes for mass transport investigations in the LIGA process

M. Lisinenkova, L. Hahn, J. Schulz
Institut für Mikrostrukturtechnik, Forschungszentrum Karlsruhe GmbH, Postfach 3640, D-76021 Karlsruhe,
Germany

Abstract

The enhancement of the knowledge of mass transport during the different manufacturing stages of high aspect ratio microstructures is important for further progress in the LIGA technology. The information about mass transport characteristics is essential in order to find the optimal processing parameters for the development and the electroforming.

A new construction and fabrication method for recessed rotating microelectrodes (RRME) for mass transport investigations in micro technology is presented. The manufacturing of these electrodes based on the LIGA process is described. This technology was tested in practice, its deficiencies were discovered and a new improved technology was presented. The improvement includes a substitution of electrochemical gold deposition to vapor deposition and using an alternative glue, which provides sufficient PMMA to gold adhesion.

The fabricated RRMEs were tested in electrochemical ferro/ferricyanide system and the first test results are reported. It has been shown that RRME, produced by improved technology, meet qualifying requirements and can be used for mass transfer investigations in micro technology

Keywords: fabrication technology, recessed rotating microelectrodes (RRME), LIGA process

Fabrication of a solenoid-type inductor with electroplated NiFe magnetic Core by MEMS

Chong Lei a, Wen Ding a, Yong Zhou a, Xiao-Yu Gao a, Hyung Choi b, Jonghwa Won b

a National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Institute of Micro and Nano Science & Technology, Shanghai Jiao Tong
University, Shanghai 200030, China (corresponding author: yzhou@sjtu.edu.cn)

b Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., 416 Maetan-Dong, Yeongtong-Gu, Suwon, Kyungki-Do 442-742, Korea

Abstract

A solenoid-type inductor was fabricated by MEMS (Microelectromechanical Systems) technique. NiFe film was electroplated as the magnetic core, and polyimide with a low relative permittivity was used as the insulation material. In the fabrication process, UV-LIGA, dry etching, fine polishing and electroplating technique have been adopted to achieve high performance of the solenoid-type inductor. The inductor was in size of 3.9 mm × 2.66 mm × 80 μm with coil width of 20 μm, space of 35 μm and aspect ratio of approximately 4:1. The inductance was 1.973 μH at a frequency of 1 MHz, and the maximum quality factor was 1.52 at a frequency of 2.14 MHz with an inductance of 1.82 μH, which is attractive for the applications of micro DC/DC converter.

Keywords: Inductance, NiFe magnetic core, MEMS, solenoid-type inductors, quality factor

Fabrication of a solenoid-type inductor with electroplated NiFe magnetic Core by MEMS

Chong Lei a, Wen Ding a, Yong Zhou a, Xiao-Yu Gao a, Hyung Choi b, Jonghwa Won b
a National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and
Microfabrication of Ministry of Education, Institute of Micro and Nano Science & Technology, Shanghai Jiao Tong
University, Shanghai 200030, China (corresponding author: yzhou@sjtu.edu.cn)

b Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., 416 Maetan-Dong,
Yeongtong-Gu, Suwon, Kyungki-Do 442-742, Korea

Abstract

A solenoid-type inductor was fabricated by MEMS (Microelectromechanical Systems) technique. NiFe film was electroplated as the magnetic core, and polyimide with a low relative permittivity was used as the insulation material. In the fabrication process, UV-LIGA, dry etching, fine polishing and electroplating technique have been adopted to achieve high performance of the solenoid-type inductor. The inductor was in size of 3.9 mm × 2.66 mm × 80 μm with coil width of 20 μm, space of 35 μm and aspect ratio of approximately 4:1. The inductance was 1.973 μH at a frequency of 1 MHz, and the maximum quality factor was 1.52 at a frequency of 2.14 MHz with an inductance of 1.82 μH, which is attractive for the applications of micro DC/DC converter.

Keywords: Inductance, NiFe magnetic core, MEMS, solenoid-type inductors, quality factor

Surface micromachined three-dimentional solenoid-type inductor

Dong-Ming Fang, Yong Zhou, Wen Ding, Xi-Ning Wang, Xiao-Lin Zhao
National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Institute of Micro and Nano Science & Technology, Shanghai Jiao Tong University,
Shanghai 200030, China (corresponding author: yzhou@sjtu.edu.cn)

Abstract

Miniaturized integrated inductor of high performance is very important in mobile communications and microwave integrated circuits. Existing on-chip spiral inductors based on conventional planar integrated-circuit fabrication technology suffer from substrate loss and parasitics, and have relatively large area. In this paper, We present the design, fabrication, and performance of surface micromachined on-chip three-dimentional (3-D) aircore solenoid microinductors. The fabricated microinductors are characterized at high frequencies from Sparameter measurements. The resulting 7-turn air-core solenoid inductors have inductances between 1.03 to 1.81 nH, peak quality (Q) factors between 19.1 to 38.0 at peak-Q frequencies between 4.4 to 6.0 GHz, and selfresonant frequencies between 10.5 and 13.0 GHz.

Keywords: Inductor, RF MEMS, quality factor, 3-D

Development of a MID LED housing

R. M. de Zwart, R. A. Tacken, P.J. Bolt
TNO Science & Industry, De Rondom 1, P.O.Box 6235, 5600HE Eindhoven, The Netherlands

Abstract

The development of microdevices would be well served by integration of electronic connects into 3D packaging. A number of technologies have been proposed in which conductive paths are created on polymer structures, of which MID (Molded Interconnect Device) technology excels in 3-dimensional flexibility. In this study, the feasibility of manufacturing a three-colour light emitting diode housing with MID technology is demonstrated. Requirements with respect to connection to the housing included absence of wire bonding and SMT relflow solderability. Two technologies were investigated: (i) two-component molding using pre-catalysed LCP and (ii) SKW process with polyamide 4,6. In both processes successive electroless copper deposition was used followed by nickel and gold coating to obtain good olderability. In processing the pre-catalysed LCP the critical step appeared to be the initial electroless copper deposition which requires tight control to obtain the metallization selectivity required. In the SKW process proper handling of parts in the catalytic activation step between molding the first and second shot is the main factor influencing yield and quality. A fairly large number of products were made with both technologies on lab scale. The finished housings were assembled on a PCB in a reflow solder process and performance of the products was evaluated positively with respect to mechanical integrity as well as electrical behaviour.

Keywords: molded interconnect devices, metallization, integrated electronics, two-component molding, LED

Micropart manipulation by electrical fields for highly parallel batch assembly

P. Lazarou, N.A. Aspragathos, Erik Jung *
Robotics Group, Department of Mechanical Engineering and Aeronautics, University of Patras, Patras T.K.
26500, Greece

* Chip Interconnection Technologies, Fraunhofer IZM, 13355 Berlin, Germany

Abstract

This paper depicts the concept of micro part manipulation by electrical fields to achieve a high precision, highly parallel batch assembly of components required to put Microsystems together. The concept of orienting microparts in 3D as well as precision alignment on a temporary precision carrier substrate is described and simulations are performed to identify an optimal configuration of the electrical field. In order to move the microparts, they are included in a liquid droplet of high dielectric constant, allowing for fast movement and easy control. The concept implementation idea is briefly described and the required electrode structure is depicted.

Keywords: MEMS, 3D manipulation, force fields, electrowetting

Design and Manufacturing of Micro Heaters for Gas Sensors

Per Johander 1, Igor Goenaga 2, David Gomez 2, Carmen Moldovan 3, Oana Nedelcu 3, Petko Petkov 4, Ulrike Kaufmann 5, Hans-Joachim Ritzhaupt-Kleissl 4, Robert Dorey 5, Katrin Persson 6

1 IVF- Industrial Research and Development Corporation; Argongatan 30, S431 53 Molndal, Sweden,
2 Fundacion Tekniker, Micro and Nanotechnology Department, Av. Otaola 20, 20600 Eibar, Spain
3 National Institute for R&D in Microtechnologies, Erou Iancu Nicolae 32 B, Bucharest 077190, Romania
4 Manufacturing Engineering and Multidisciplinary Technology Centre, Cardiff University;
5 Forschungszentrum Karlsruhe, Institut für Materialforschung III, P.O. Box 3640, 76021 Karlsruhe, Germany ;
5 Nanotechnology Group, Cranfield University, Cranfield, Bedfordshire, UK;
6 IMEGO, Arvid Hedvalls Backe 4, SE 411 33 Goteborg, Sweden;

Abstract

The paper presents the design and manufacturing steps of micro heaters, built on ceramic suspended membranes for gas sensor applications. The micro heaters are designed and fabricated by combining laser milling techniques, and conductive ceramic technology. Trenches are created in the ceramic substrate in order to define the geometry of the heater using laser processing of the substrate. The heater is completed by filling the trenches with conductive ceramic paste and then baking to remove the solvent from the paste. The final step involves releasing the membrane by laser milling, enabling it to be suspended on four bridges, to minimise the dissipation of the heat in the substrate. The temperature of the heater element was measured with a heat camera from FLIR 40 system comparing the case of the heater positioned on top of a released membrane and that of the non-released membrane. The simulation of the heater build on top of a released membrane was compared with the heater measurements.

Keywords: Micro heaters, gas sensor

Developments in Micro Ultrasonic Machining (MUSM)

J.J. Boy*+, M. Aiguillé**, A. Boulouize**, C. Khan-Malek***

* FEMTO-ST / LCEP - 26 chemin de l'Epitaphe - 25000 BESANCON - France
** TEMIS Innovation (Projet μUSM) - 18, rue A. Savary - 25000 BESANCON - France
*** FEMTO-ST / LPMO - 32, avenue de l'Observatoire - 25030 BESANCON Cedex
+ Corresponding author : Tel : 33 (0) 3 81 40 28 23 ; E-mail : jjboy@ens2m.fr

Abstract

Ultrasonic machining (USM) presents a particular interest for the cutting of non-conductive, brittle materials such as ceramics, glasses or fused silica and quartz crystal. Unlike other non-traditional processes such Electrical Discharge Machining (EDM and micro-EDM, adapted to conductive materials), laser ablation or wet chemical etching, USM does not thermally damage the workpiece and does not create significant levels of stresses. Production of complex 3-D shapes with a volume of a few cubic millimeters is presented.

Keywords: Ultrasonic machining, micro technology, aspect ratio, tool wear, PZT.

The effects of material microstructure in micro-milling

K. Popov a, S. Dimov a, D. T. Pham a, R. Minev a, A. Rosochowski b, L. Olejnik c, M. Richert d

a Manufacturing Engineering Centre, Cardiff University, Cardiff, UK,
b Design, Manufacture and Engineering Management, University of Strathclyde, UK,
c Institute of Materials Processing, Warsaw University of Technology, Warsaw, Poland,
d Faculty of Non-Ferrous Metals, AGH - University of Science and Technology, Krakow, Poland

Abstract

Micro-milling is one of the technologies that is currently widely used for the production of micro-components and tooling inserts. To improve the quality and surface finish of machined microstructures the factors affecting the process dynamic stability should be studied systematically. This paper investigates the machining response of a metallurgically and mechanically modified material. The results of micro-milling workpieces of an Al 5000 series alloy with different grain microstructure are reported. In particular, the machining response of three Al 5083 workpieces whose microstructure was modified through a severe plastic deformation was studied when milling thin features in microcomponents.

The effects of the material microstructure on the resulting part quality and surface integrity are discussed and conclusions made about its importance in micro-milling. The investigation has shown that through a refinement of material microstructure it is possible to improve significantly the surface integrity of the micro-components and tooling cavities produced by micro-milling.

Keywords: micro-milling, material microstructure, grain size effects

Laser Micro-milling of Ceramics, Dielectrics and Metals using nanosecond and picosecond lasers

M.R.H Knowles a, G. Rutterford a, D. Karnakis a, T. Dobrev b, P.Petkov b, S.Dimov b

a Oxford Lasers Ltd, Unit 8, Moorbrook Park, Didcot, OX11 7HP, UK
b MEC, Cardiff University, Newport Road, Cardiff, CF24 3AA, UK.

Abstract

Laser micro-milling of industrial materials like ceramics, dielectrics and metals is of significant commercial interest for fabrication of micro-moulds and other micro-system devices. 2.5D laser machined structures were generated in alumina, tungsten and steel substrates using a nanosecond copper vapour laser (511nm) at 10 kHz. Preliminary results in fused silica, alumina and steel are also presented from a high repetition rate amplified mode-locked picosecond Nd:vanadate laser. It is shown that high quality surface finish can be achieved with both laser types; for example, average surface roughness, Ra ~ 300nm has been demonstrated in steel. Fused silica could only be processed with picosecond laser pulses. Volume removal rates are analysed, which are especially high for difficult materials like tungsten (~0.1mm3/min) and are greater compared to other milling technology like micro-EDM. Surface roughness measurements in these materials using white light interferometry are reported along with SEM analysis.

Keywords: laser, micro-milling, ceramic, dielectric, metal, ceramic, nanosecond, picosecond

Dimensional tolerances of micro precision parts made by ceramic injection moulding

M. Beck a, V. Piotter a, R. Ruprecht a, J. Haußelta,b
a Institute for Materials Research III, Forschungszentrum Karlsruhe GmbH, P.O. Box 3640, D-76021 Karlsruhe, Germany, e-mail: martin.beck@imf.fzk.de
b Institute of Microsystem Technology (IMTEK), University of Freiburg, Georges-Köhler-Allee 102, D-79110 Freiburg, Germany

Abstract

The aim of the study is to analyse the dimensional variation in ceramic injection moulding of micro precision parts made of zirconia ceramics in order to improve the quality of the injection-moulded parts and to reduce costly reworking of the sintered parts. Dimensional variation and surface quality of injection- moulded single-mode ferrules in the green and sintered state were measured with high precision in the sub-micrometre range. The influence of the process parameters on dimensional tolerances and surface quality of the parts was analysed. Furthermore, the dimensional tolerances and surface quality of the mould cavity used were measured and compared with those of the moulded parts. The results show that process parameters in injection moulding strongly influence the absolute dimensions as well as the dimensional scatter of the green compacts and sintered parts. The coefficient of variation of the outer diameter of the sintered ferrules (nominal value 2.5 mm) was between 0.2% and 0.3%. Furthermore, the injection-moulded green compacts showed shape deviations which could not be explained by the shape tolerance of the mould insert.

Keywords: PIM, CIM, micro precision ceramic injection moulding, optical ferrule, zirconia