Dynamical IMC-growth calculation

Abstract Material movement between solder joints and their contact pads leads to the formation of intermetallic compounds at the contact surfaces. Concentration gradients are responsible for this material movement. The intermetallic compound growth during temperature storage and AC/DC electromigration tests on 12 × 12 mm Amkor® PoP with SnAg 3.0 Cu 0.5 ball grid arrays including direct SnAgCu to Cu contacts at their bottom bumps was investigated. Based on the resulting increase in the IMC thickness the average mass flux of Cu and Sn were calculated. The activation energies (E A ) diffusion constants (D 0 ), effective charges (Z*) and heats of transport (Q*) are determined by measurement. With these parameters the mass fluxes due to concentration gradients, electromigration and thermomigration are calculated and the results were implemented in a routine for the dynamical calculation of the IMC-growth. Finally these calculations were validated by measurements.

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