Johnson Matthey Inc.

Avx Corporation

Raymond L Dietz

Michael Featherby

Peter K Margetts

A silver metallizing paste for attachment of silicon semi-conductive devices in lead-frame packages, specifically ceramic packages, which is less expensive than a gold preform but useable in hermetic packages, and provides better electrical and thermal conductivity, and higher bond strength, than silver polyimides. From 25 to 95% of silver is blended with a low-melting glass, preferably one having 95-96% PbO, and a paste or ink is formed with a suitable vehicle at 75-85% solids. Use of the paste follows conventional practice. Selection of Ag:glass ratio depends on the type of die bonding to be used. The paste is particularly useful in MOS technology, where low contact resistance is required, and also finds applications as a solder substitute and bonding chip capacitors. It is most advantageous in attachment of larger-area integrated circuits in that stress cracking associated with the gold-silicon eutectic is avoided.

Method of bonding an electronic device to a ceramic substrate

Silver-filled glass

Hermetically sealed unit containing an integrated circuit metal oxide semi-conductor chip, wherein a single layer gold-silver alloy serves both to secure the chip within the unit and to form a proper junction with the aluminum alloy conductor connected to a circuit element in said chip. A sufficient proportion of silver is included in the gold-silver alloy whereby said junction retains requisite operational characteristics of bond strength and low resistivity when said unit is subjected to heat for providing a hermetic seal therefor.

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Poway, CA, United States of America

Raymond L Dietz