Evaluation of solder joint strengths under ball impact test

The ball impact test (BIT) was developed based on the demand of a package-level measure of the board-level reliability of solder joints in the sense that it leads to brittle intermetallic fracturing, similar to that from a board-level drop test. The BIT itself stands alone as a unique and novel test methodology in characterizing strengths of solder joints under a high-speed shearing load. In this work, the BIT apparatus, characteristics of measured impact force profiles, and induced failure modes are introduced. We also present BIT results conducted on 63Sn–37Pb, 95.5Sn–4Ag–0.5Cu, and 98.5Sn–1Ag–0.5Cu package-level solder joints, bonded on substrate pads of different surface finishes, under an impact velocity of 1 m/s or 1.25 m/s.