Characterizations of Ball Impact Responses of Tin-Silver-Copper Solder Joints Doped With Nickel or Germanium

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, we present BIT results conducted at an impact velocity of 500 mm/s on Sn-4Ag-0.5Cu, Sn-1Ag-0.5Cu, Sn-1Ag-0.5Cu-0.05Ni, Sn-1.2Ag-0.5Cu-0.05Ni, and Sn-1Ag-0.5Cu-0.05Ge package-level solder joints, bonded on substrate pads of immersion tin (IT) and direct solder on pad (DSOP) surface finishes. Differences of BIT results with respect to multi-reflow are also reported.