Multi Material Micro Manufacture Network of Excellence - Measurement / Metrology

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

Mon, 04 Aug 2008 13:57:51 +0000

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.

Manufacturing and verification of tools for ECF

Mon, 04 Aug 2008 13:26:32 +0000

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.

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

Wed, 30 Jul 2008 11:48:42 +0000

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.

Micro-ultrasonic metrology of multi-material electronic devices

Wed, 30 Jul 2008 11:38:57 +0000

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.

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

Wed, 30 Jul 2008 11:28:10 +0000

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

Wed, 30 Jul 2008 11:21:18 +0000

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.

Metrology Applications of Two-Dimensional Frequency Analysis for Micro-Features Characterisation

Tue, 20 May 2008 11:05:17 +0000

R. Teti (a), L. Mattsson (b), Andrej Lebar (c), Mihael Junkar (c)

a Department of Materials and Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, 80125 Naples, Italy
b Department of Production Engineering, KTH – the Royal Institute of Technology, SE-10044 Stockholm, Sweden
c Laboratory for Alternative Technologies, Faculty of Mechanical Engineering, University of Ljubljana, Askerceva 6, SI-1000 Ljubljana, Slovenia

Abstract

In this paper, the characterisation of micro-features involved in metrology applications within the scope of 4M is carried out through the use of different two-dimensional frequency analysis procedures. Firstly, the analysis methods are introduced and their basic principles are illustrated. Secondly, selected test cases, representing the issue of experimental research activities performed at the laboratory sites of the co-author’s partner organisations, are presented with reference to diverse metrology purposes in different fields of applications.

Assessment of digital cameras for micro-structural sensing of low contrast surface features

Tue, 20 May 2008 11:01:20 +0000

A. Temun, L. Mattsson

Department of Production Engineering, KTH – the Royal Institute of Technology, SE-100 44 Stockholm, Sweden

Abstract

Evaluation of three digital cameras are presented focusing on their capabilities and applicability in the detection of low-contrast surface features on the micrometer level. The key to a successful identification of surface flaws on micro-structured surfaces, such as silicon wafers is the ability to determine minor deviations in the reflectance of an object surface. Micro-topography of a surface, surface structure and surface roughness has a strong influence on the amount and direction of scattered light. Different portions of the surrounding illumination are reflected on different parts of an uneven surface, hence the resulting contrast-variation on the illuminated surface has a strong correlation to the surface structure itself.

In our work we discuss the possibilities of using either of the investigated cameras for the automated visual inspection of micro-structured surfaces. The cameras - two of them equipped with CCD and one with CMOS image sensors - are studied in an environment which is similar to standard surface appearance measurements, involving human observers. The specimens, featuring different surface structures are imaged in a well-controlled environment under varying illumination conditions. Experimental results of spatial resolution and contrast sensitivity are presented.

Surface characterisation in forming processes by functional 3D parameters

Tue, 20 May 2008 10:57:31 +0000

S. Weidel (a), U. Popp (b), U. Engel (a)
a Chair of Manufacturing Technology, University of Erlangen-Nuremberg, Egerlandstr. 11, D-91058 Erlangen, Germany
b ThyssenKrupp Presta, FL-9492 Eschen, Liechtenstein

Abstract

Tribology in metal forming plays a significant role for process feasibility and process quality. Especially in micro forming the influence of the tribological condition is very essential due to an extensive increase in friction which is observed while scaling processes from macro to micro. As friction depends considerably on the surface topography of tool and workpiece, functional surface characterisation concerning the tribological properties becomes even more relevant. Standardised 2D roughness-measurements and -parameters are not able to fulfil this task satisfactorily. Hence the surface has to be measured three dimensionally. An appropriate method is given by confocal white light microscopy. New 3D parameters are defined with respect to the functional behaviour of the surface. These parameters are derived from a mechanical-rheological model which describes the transmission of the forming load from the tool to the workpiece. In order to calculate these parameters, the software WinSAM has been developed. Especially the maximum closed void area ratio and the volume of closed lubricant pockets have already proven their capability of characterising the tribological behaviour of the surfaces in the macro world. It is expected that these parameters are a basis for a functional characterisation of the topography in micro-forming applications as well.

Micro metrology tools for local investigation of mechanical phenomena in solids and liquids

Tue, 20 May 2008 10:53:29 +0000

P. I. Koulev, I. R. Roussev, A. Choulev

Institute of Mechanics, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria

Abstract

We will present micro metrological experiments and results from local investigation of some mechanical phenomena, such as: 1/ deformation of thin rubber plate; 2/ deformation of the free liquid surface in atmosphere; 3/ displacement of two-dimensional layer of micro particles suspended in two-dimensional liquid sheet. In the first case the plate surface deflection has been measured in the range of 0 to 0.12 μm; in the second case the free liquid surface aberration have been measured in the range of 0 to 0.3 μm; in the third case particle velocities of the order of 8 μm/s have been measured. Special computer modifications of one- and two-beam speckle-interferometry have been developed. The measurements have been realized by using of an isolated from vibrations concrete block, НеNe-laser, standard commercial optical and mechanical components, CCD cameras, PENTIUM II Celeron based PC. The results are applicable to high precision micro components (e.g. micro actuators) testing. Specially constructed micro metrological set-ups could be used on new production platforms for multi material micro products.

Through-Transmissive-Media (TTM) Interferometric Techniques Applied to Characterizing Packaged MEMS and MOEMS Devices

Tue, 20 May 2008 10:48:22 +0000

Sen Han (a), Trisha Browne (a), Mike Zecchino (a), and Udo Volz (b)

a Veeco Instruments, Inc., 2650 E. Elvira Road, Tucson, AZ 85706, USA
b Veeco Instruments GmbH, Dynamostr. 19, D-68165 Mannheim, Germany

Metrological characterization of micro particles by direct simulation Monte Carlo

Tue, 20 May 2008 10:43:56 +0000

M.D. Mikrenska (a), P.I. Koulev (a), J.-B. Renard (b)
a Institute of Mechanics, Bulgarian Academy of Sciences, Sofia, 1113, BG
b Laboratoire de Physique et Chimie de l'Environnement, CNRS, 45071 Orléans, FR

Electro-Chemical Polishing: a Technique for Surface Improvements after Laser Milling

Mon, 12 Nov 2007 16:23:32 +0000

T Dobrev, D T Pham and S S Dimov
Manufacturing Engineering Centre, Cardiff University, Cardiff, CF24 3AA, UK

Abstract

Electro-chemical polishing is a process of improving micro smoothness, micro topology, and material brightness by anodic dissolving of the substrate in an electrolyte with an external source of electricity. The resulting surface improvements depend on the uniformity of the material microstructure, the lack of surface inclusions, and the consistency of the surface finish all over the target area. In contrast, laser milled structures are mostly concave features; their roughness is usually higher than that achieved on the other surfaces of the component, and also there is a significant presence of foreign or recast particles on them. Thus, it is important to investigate systematically the effects of electro-chemical polishing on microstructures machined by laser milling.

The paper discusses the effects of electro-chemical polishing on the surface finish of laser milled features. Although ECP displayed some limitations when polishing micro features, it still managed to achieve almost 30% improvements in omparison to the initial roughness after laser milling. Another benefit is that the process also improves the edge quality of the laser machined structures by removing the burrs.

A New Method for Directly Determining the Adhesive Strength of Conductors on Microstructured MID

Mon, 12 Nov 2007 16:23:32 +0000

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

Through miniaturisation and 3D capability moulded interconnect devices (MID) offer great opportunities for various applications in a broad industrial field. Especially, when applying the laser-direct-structuring process of the company LPKF (LPKF-LDS® process) fine conductors can be fabricated on thermoplastic substrates. A main criterion for the industrial application is the adhesive strength of the conductors. As for LDS MID there is currently no suitable test method for directly determining the adhesive strength of conductors. Therefore, a measuring device consisting of a sensor and peel off unit has been developed at HSG-IMAT. It has been used to investigate a measuring principle utilising a peel off chisel for adhesion determination. Promising and repeatable results have been obtained by testing conductors on thermoplastic substrates.

Non-Destructive Characterization of Multilayer Structures by Low-Coherence Interferometry

Mon, 12 Nov 2007 16:23:32 +0000

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

Abstract

We present here a non-destructive technique for characterization of multilayer structures based on low-coherence interferometry. This technique is capable to give information of physical thickness and index of refraction of the subjected sample regardless of how many different layers exist along the optical trip. The main limitation is if the investigated materials are transparent for the used optical wavelength. We performed sensing set up in the form of single-mode fiber-optic Michelson interferometer composed of one 2×2 optical coupler. There were tested three and five layers foils composed of sandwich structure made by alternation of polyarilate (PAR) and glue layer. We achieved a success discriminate the interface between the two different materials with accuracy of about 40 nm by analyzing low-coherence interferograms.