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Proceedings Paper

Versatile microflex-based interconnection technique
Author(s): Hansjoerg Beutel; Thomas Stieglitz; Joerg-Uwe Meyer
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Paper Abstract

A new interconnection technique has been developed that allows versatile multiple strand connections between microsensors, sensor arrays, and chips designed for wire bonding. The new technique has been termed `microflex interconnects' (MFI). Conventional wire bonding technique is commonly restricted to planar interconnects with a limited degree of freedom for placing microsystem components. The MFI technique has overcome this limitation by interconnecting microsystem components through custom designed flexible foils with embedded metallized conductors. The MFI foils may also serve as circuit substrates. This basic foil material is polyimide (Du Pont PI 2611) or BCB which are patterned photolithographically. Platinum, gold or either conductive metals are sputtered or evaporated on the foil and patterned using lift-off technique. Several metallization layers can be embedded in the material. Pitch and shape of the MFI contact pads correspond to the one of the chips to be interconnected. A via hole is placed in the center of the MFI contact pads. MFI pads and chip pads are adjusted. Metal balls or wedges generate the electrical and mechanical contact through the vias between the chips and the MFI substrate. An commercial wire bonder is the only equipment needed to perform the MFI method. The MFI technique was applied to bond standard CMOS integrated circuit bond pads with a width of 30 micrometers and a pitch of 70 micrometers to a 10 micrometers thick MFI foil. The integration density of the of the MFI technique correspond to one of the flip- chip technology. Special advantages of the MFI technique are 3D interconnects, the flexibility in design and shape, and easy visual inspection of alignment qualities. The MFI method is also suited for biomedical applications because all materials used are biocompatible.

Paper Details

Date Published: 20 July 1998
PDF: 9 pages
Proc. SPIE 3328, Smart Structures and Materials 1998: Smart Electronics and MEMS, (20 July 1998); doi: 10.1117/12.320167
Show Author Affiliations
Hansjoerg Beutel, Fraunhofer Institute for Biomedical Engineering (Germany)
Thomas Stieglitz, Fraunhofer Institute for Biomedical Engineering (Germany)
Joerg-Uwe Meyer, Fraunhofer Institute for Biomedical Engineering (Germany)

Published in SPIE Proceedings Vol. 3328:
Smart Structures and Materials 1998: Smart Electronics and MEMS
Vijay K. Varadan; Paul J. McWhorter; Richard A. Singer; Michael J. Vellekoop, Editor(s)

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