MECHANICAL RESPONSE OF SOLDER JOINTS IN FLIP-CHIP TYPE STRUCTURES

The mechanical response of PbSn solder joints of two different solder alloys (37 wt.% Pb - 63 wt.% Sn and 95 wt.% Pb - 5 wt.% Sn) used as fl ip-chip type interconnects is measured through mechanical testing (in tension and in shear). The influence of solder pad composition (Au and Ni) upon the behaviour of the solder joints is examined. Fatigue test ing performed upon flipchip samples demonstrates the difference in mec hanical comportment between Pb37Sn63 and Pb95Sn5 solders, A model for predicting fatigue life is put forward. (C) 1997 Elsevier Science Ltd.