Solder Volume Effect on Interfacial Reaction between Sn-3.0Ag-0.5Cu Solder Balls and Cu Substrates - Experiment & Simulation

With the continuous miniaturization of electronic devices, solder joints are downsizing simultaneously. The downsizing of the solder balls may have a detrimental effect on the reliability of the solder joints. Because smaller solder joint has thicker intermetallic compound (IMC) layer which may degrade the mechanical properties of the solder joints. The solder volume effect on interfacial reaction was demonstrated in the present work. It was shown that, when the smaller solder ball was used, the Cu6Sn5 grains became larger and the interfacial intermetallic compound (IMC) layer became thicker, which were accompanied by less Cu consumption and higher Cu concentration in molten solder. A theoretical model was established to calculate the growth kinetics of the interfacial IMC and the consumption kinetics of the Cu pad during the liquid/solid reaction. The calculated results were compared with the experimental ones, and a good agreement was achieved.