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Composite Structures for Modifying Thermal Coefficient of Expansion

IP.com Disclosure Number: IPCOM000090448D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Blodgett, AJ: AUTHOR [+2]

Abstract

The reduction in strain in the joint between a silicon semiconductor chip mounted on ceramic substrate is proportional to the reduction in the mismatch between the ceramic and the silicon materials.

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Composite Structures for Modifying Thermal Coefficient of Expansion

The reduction in strain in the joint between a silicon semiconductor chip mounted on ceramic substrate is proportional to the reduction in the mismatch between the ceramic and the silicon materials.

Silicon, for the purpose of comparison, has a temperature coefficient of expansion TCE of 35 x 10/-7/ in/in/ degree C. The ceramic substrate can be made to more closely match the silicon TCE and other properties by providing a composite of alternate layers of ceramic and a metal for the substrate. If the mismatch of the components of the composite which is projected for use is high, it is necessary to match their modulus of elasticity so that the stronger member does not rupture the weaker member during a thermal excursion.

If there is close match in TCE this is less important. It is not essential that one member be a nonconductor both members can be. The structure need not be limited to two members.

Examples of composites that are suitable follow.

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Note Zircon should be a suitable match for Silicon. Tungsten is intended to improve the thermal conductivity of the composite.

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