Effect of Added Elements on Microstructures and Joint Strength of Lead-Free Sn-Based Solder Joint Dispersed IMC Pillar

Abstract

To create a high reliability solder joint using IMCs dispersed in the joint, the joints with four types of lead-free solder were investigated. The joint with Sn-3.0Ag-0.7Cu-5.0In (mass%) has high die shear force compared to other joints investigated, and the joint with the Ni-electroplated Cu bonded at 300 oC for 30 min showed the maximum die shear force due to formation of a large number of fine IMCs. In the joint with Sn-0.7Cu-0.05Ni (mass%), uniform dispersion of a large number of IMCs was achieved, although the die shear force of the joint is lower than that of the joint with Sn-3.0Ag-0.7Cu-5.0In. In the joint with Sn-5.0Sb (mass%), a solder area was remained in the center of the joint although a large number of columnar IMCs form at the joint interface. The die shear force of the joint with Sn-5.0Sb increased with increasing the bonding time due to formation and growth of IMCs. In the joint with Sn-3.0Ag-0.5Cu (mass%), IMCs formed at the joint interface and did not disperse in the entire joint.

Effect of Cooling Rate on Intermetallic Compounds Formation in Sn-Ag-Cu-In Solder

“…In a power module that is required larger area bonding compared to general electronic components, suppression of crack growth in a solder joint is effective to improve the reliability of the joint. The authors have developed the solder joint with pillar-shaped intermetallic compounds (IMC) for automotive applications to suppress the progress of the crack [2][3][4]. In the previous study, the effect of bonding conditions on the formation of pillar-shaped Cu-Sn IMCs was researched with several lead-free solder [2].…”