Effect of Cu Leadframe Substance on Whisker Initiation Behavior in Electrodeposited Sn-Cu Coating

Abstract

Drastically different tendencies of whisker initiation were observed from the same electrodeposited Sn-Cu coating on two Cu leadframe materials, CUFE and CUCR, after long-term storage at room temperature. No whisker was observed for Sn-Cu/CUCR lead, whereas long whiskers were formed from Sn-Cu/CUFE. Effects of the doped minor elements in Cu leadframe on morphology of Cu-Sn compound formed in the lead, and on compressive stress in the coating were investigated through microstructural evaluation and X-ray diffraction measurement. Controlling model for whisker initiation was described.