A Study on Reliability of Pillar-Shaped Intermetallic Compounds Dispersed Lead-Free Solder Joint

Abstract

A pillar shaped intermetallic compounds (IMCs) dispersed solder joint is a highly durable joint to achieve large area joining. The aim of this study is to investigate the ideal dispersion amount of pillar shaped IMCs. The dispersion rate of pillar shaped IMCs depend on the joining temperature. Pillar shaped IMCs dispersion rates are 3.5% and 5.5% when the joining temperature are 300 °C and 330 °C, respectively. Longitudinal elastic modulus are improved by forming pillar shaped IMCs. As a result of examination of the durability by the thermal cycle test, the durability of the joint with the dispersion rate of 3.5% was similar to that without pillar shaped IMCs, while that with the dispersion rate of 5.5% was remarkably improved. In the case of the dispersion rate of 3.5%, pillar shaped IMCs unevenly distributed and cracks tend to progress. On the other hand, in the case of the dispersion rate of 5.5%, pillar shaped IMCs were uniformly dispersed throughout the joint and suppressed crack propagation. Comparison of durability between pillar shaped IMCs solder and indium added solder to verify the effect of pillar shaped IMCs demonstrated that pillar shaped IMCs solder were more durable than indium added solder.