Abstract:

Potential failure mechanisms in high density interconnects (HDI) due to mismatches in coefficients of thermal expansion and mismatches in coefficients of hygroscopic expansion are investigated.  A section of an HDI package is modeled and analyzed for change in ambient relative humidity from 30% to 90% and temperature distribution during operation characterized by a junction temperature of 73ºC.  The analyses reveal that the hygro-mechanical stresses are more detrimental than the thermo-mechanical tresses to the metallization/polyimide interfaces.  However, in both cases, the polyimide films are under compressive stresses.  These stresses can potentially lead to micro-buckling in the polyimide films and promote interfacial de-adhesion between the metallization and polyimide film due to large localized strains.

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