Correlation study between intermetallic layer and drop test for polymer core leadlead-free solder ball under reliability test

Abstract

Polymer core coated lead-free solder ball is one of an alternative in integrated circuit (IC) packaging interconnection. In order to verify the performance of polymer core coated solder balls, the reliability comparison of Nickel (Ni)-coated polymer core solder ball with non-coated polymer solder ball is carried out. The polymer core solder ball is coated with 1 μm thickness of Nickel (Ni) on the Copper (Cu). In this study, different thermal cycles; Temperature Cycle (TC) up to 1000 cycles and Autoclave (AC) up to 168 hours and tray drop test have been used to inspect the solder ball joint handling and impact force robustness. The results show that Ni-coated polymer core solder ball shows thinner IMC and better performance in drop test under TC and AC stress test compared than that of non-coated polymer solder ball. Thinner IMC provide better drop performance and vice versa.

Keywords: Polymer-core-coated-solderball; Intermetallic Compound; Thermal stress