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Browse Prior Art Database

COMPLIANT INTERCONNECT METHOD AND STRUCTURE

IP.com Disclosure Number: IPCOM000005754D
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2001-Nov-02
Document File: 2 page(s) / 91K

Publishing Venue

Motorola

Related People

Bernard Greenstein: AUTHOR [+2]

Abstract

This invention describes a means to reduce thermal shock fatigue using a compliant soldering member. It involves the use of a flex circuit.

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MOTOROlA Technical Developments Volume 6 October 1968

COMPLIANT INTERCONNECT METHOD AND STRUCTURE

by Bernard Greenstein and Ted Grzeskowiak

This invention describes a means to reduce thermal shock fatigue using a compliant soldering member. It involves the use of a flex circuit.

   The present interconnection art has the problem of high mismatches in thermal expansion coefficients of bonded materials causing high stresses and early failure of units when thermally cycled. Figure 1 is represen- tative of the prior art interconnection system involving soldering a lead frame 1 embedded in a plastic housing 9 to a metallized ceramic (A1201) substrate 3 mounted on an aluminum heatsink base plate 4. Mismatch in the coefficient of thermal expansion of the aluminum base plate 4, metallized aluminum oxide ceramic substrate 3, plastic housing 9 and metal lead frame 1 causes undue strain on solder joints. A way to minimize this effect is to put strain relief in the lead frame 1 and, therefore, make it as thin and as narrow as possible to give the lead compliancy to take up any expansion mismatch. This improves the situation somewhat. Another approach is to solder or wire bond or weld wires from the embedded lead frame 1 to the metallized pads on the substrate 3, the wires having a loop in them to provide some compliancy. This also represents somewhat of an improvement.

   The present invention (Figs. 2 and 3) uses a totally flexible, compliant connection between the lead frame 2 and the metallized substrate 3, which comprise aluminum oxide (Al201), but wherein the substrate can be made of any suitable material such as AIN or any other low expa...