Browse Prior Art Database

Matching the Thermal Coefficients of Expansion of Chips to Module Substrate

IP.com Disclosure Number: IPCOM000088270D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Liu, CN: AUTHOR

Abstract

The problem of thermal expansion mismatch exists between semiconductor device chips (silicon or germanium) and substrates such as Al(2)O(3), BeO and plastic. This mismatch causes fatigue failure of solder balls or beam leads on modules which is one of the greatest concerns in packaging. The technique described will eliminate this thermal mismatch, thus eliminating the fatigue mechanism, giving a longer life to solder balls or beam leads.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 62% of the total text.

Page 1 of 2

Matching the Thermal Coefficients of Expansion of Chips to Module Substrate

The problem of thermal expansion mismatch exists between semiconductor device chips (silicon or germanium) and substrates such as Al(2)O(3), BeO and plastic. This mismatch causes fatigue failure of solder balls or beam leads on modules which is one of the greatest concerns in packaging. The technique described will eliminate this thermal mismatch, thus eliminating the fatigue mechanism, giving a longer life to solder balls or beam leads.

This technique eliminates the source of the thermal mismatch between ; the chip and substrate either entirely or partially, as the designer requires. Thermal expansion coefficients of several materials are listed below: Thermal Expansion Coefficient

Material (in/in-degrees C)

Silicon chip 2.5 x 10/-6/

Al(2)O(3) substrate 6.0 x 10/-6/

BeO substrate 9.0 x 10/-6/

Plastic Sbstrate 20~50 x 10/-6/

Copper 17 x 10/-6/

EPON* 828 + Epi 841 + 70% Al(2)O(3) 28.4 x 10/-6/

This mismatch is evident between a silicon chip and an Al(2)O(3) substrate and even more evident between a silicon chip and plastic substrate.

This technique uses as a compensator, a material having a higher thermal expansion coefficient, such as copper, BeO or stainless steel. This material is bonded to the device chip such that the composite structure of this material and device chip will have a perfect match or closer match to the substrates for thermal expansion coefficient. Thus, it eliminates t...