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Control of Thermal Coefficient of Expansion of Substrate Materials

IP.com Disclosure Number: IPCOM000087360D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Dougherty, WE: AUTHOR

Abstract

The thermal mismatch between metal clad organic laminates and silicon chips has precluded the use of such laminates as direct facedown semiconductor chip attach vehicles. If the coefficient of expansion (alpha) can be more closely matched to that of the silicon, the solder joint life between chip and laminate will increase and thereby allow the use of organic laminates as first level package.

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Control of Thermal Coefficient of Expansion of Substrate Materials

The thermal mismatch between metal clad organic laminates and silicon chips has precluded the use of such laminates as direct facedown semiconductor chip attach vehicles. If the coefficient of expansion (alpha) can be more closely matched to that of the silicon, the solder joint life between chip and laminate will increase and thereby allow the use of organic laminates as first level package.

The alpha of an organic laminate 1 can be influenced by including in the composite structure a material with a sufficiently different coefficient of expansion. If this material 2 is placed close enough to the top laminate surface, the solder joints 3 to a semiconductor chip 4 will see a lower alpha than the organic laminate itself. This can increase joint life to equal or greater than the presently used ceramic substrate. These planes 2 can simultaneously serve as power planes (ground or voltage). Clearance holes for pins 5 would have to be provided in the plane. Coefficient of expansion planes 2 can be formed of, for example, molybdenum (alpha = 5.2 x 10/-6/ in/ degrees C) or similar metals.

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