Solder Joint Reliability Investigation of Chip Scale Package with Plastic Core Solder Balls on Thermomechanically Loaded PCBs

In this paper, solder joint reliability of a Chip Scale Package (CSP) with polymer core solder balls (PCSB) was evaluated. Temperature cycling data was obtained from both conventional and polymer core balls tested on chip scale package with pitch 0.5mm mounted on an 8 layers HDI board. FEM simulation was also performed to compare the polymer core balls with a conventional solder ball. This study has clearly shown that the reliability of polymer core solder balls is strongly dependent on manufacturing, method of assembly (balling), package type (BGA or WLP) and the solder joint shape. Polymer core solder balls may potentially improve solder joint fatigue life, but the significant effects of design variables define the achievable benefits.