4M Knowledge base - papers

A new approach in polymer waveguide fabrication

Severin Dahms, Frederik Bundgaard and Oliver Geschke
MIC - Department of Micro and Nanotechnology, Technical University of Denmark (DTU), Building 345 East, 2800 Kgs. Lyngby, Denmark


Waveguides are an excellent means of integrating sensor components in single use microfluidic polymer systems. However, most processes for producing on-chip waveguides require several process steps, some of which are not suited for mass production. We report a simple procedure in which two different grades of the cyclic olefin copolymer (COC) Topas® are used as substrate and core layer. In a spin coating process a Topas® grade with high refractive index is spin coated onto the injection moulded substrate with lower refractive index, thereby generating a core layer. A simple hot embossing process enables simultaneous structuring of waveguides and microfluidic channels in the core layer. In a final step the microfluidic structures can be closed with a lid, either by thermal bonding or by laser transmission welding.

The refractive index and glass transition temperature Tg can be altered by changing the ratio between the two copolymers of Topas®. The low optical transmission loss of the material, along with its chemical resistance and low water absorption, makes Topas® a good choice for making integrated optics in microfluidic systems.

Submitted on May 19, 2008 - 13:44.

A New Approach to Qualitiy Assurance in Resistance Welding for Microsensors Packaging

D. Ulieru(a), Alina Matei(b), Elena Ulieru(c), A. Tantau(c)
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


The permanent development of microelectronics technologies provide new challenges for miniaturization and complexity increasing for new packaging technologies. So the exciting applications for microsystems, sensors and actuators production are looking for the best quality hermetic sealing of metal packages. The paper showed our researches and experiments results for a new approach to quality assurance in resistance welding. These will analyze the main causes of weld failures and also our methods of determining its value. On the basis of this requirement have monitored through the weld sequence, integrated concept of power monitor. The technical features developed a modern concept applicable to a wider range of fields. Our monitor could be used to wide range of welding technologies like distributed spot and focused spot, projection, roller spot and mash welding machines, working with single or three phase, ac. or dc. The experiments with our equipment have proven its advantage for fast production assembly line.

Submitted on November 12, 2007 - 16:23.

A New Concept for an Absolutely Encoded Angular Resolver

V. Mayer, T. Botzelmann, K.-P. Fritz, J. Seybold, H. Kück
Hahn-Schickard-Gesellschaft, Institute of Micro Assembly Technology, Allmandring 9b, 70569 Stuttgart, Germany


At HSG-IMAT a new concept for an absolutely encoded optical angular resolver has been developed. The key element of the sensor concept is a disc with a high precision solid measure which is fabricated using the well known manufacturing process for compact discs (CD-Technology). Using this process, it is possible to fabricate a high precision solid measure in high quantities and at low manufacturing costs. To detect the absolute angular position, a laser beam is focused onto the solid measure. The beam is deflected by the diffractive gratings of the solid measure, whereupon the different first orders fall onto separated elements of a photo diode array. To verify the principle of operation an experimental setup assembled under a microscope, with a CCD-chip instead of a photodiode array, was used to demonstrate the signal modulation. Based on these experiments, a small size demonstrator device was designed and assembled. The successful experimental results with this demonstrator device show the large potential of this new sensor concept for different applications.

Submitted on November 12, 2007 - 16:23.

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

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


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.

Submitted on November 12, 2007 - 16:23.

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


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.

Submitted on July 29, 2008 - 13:46.

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