Effects of gold on the properties of tin-antimony solder in flip-chip-pin-grid-array (FCGPA) packages

The physical characteristics of the tin-antimony solder used in FCPGA semiconductor packages change with the diffusion of gold from the gold plated layers in the solder pads or pin. This must be considered in the setting of parameters for the subsequent re-flow processes and also the possible impact on the quality and reliability of the joints. This work describes the physical and micro-structural properties of the 95Sn5Sb parent material alloyed with 1.0, 2.0, 2.5, 3.0, 3.5, 4.0 and 5.0 wt% of gold. In particular, the melting behaviour, electrical and thermal conductivity and hardness of 95Sn5Sb solder doped with gold are discussed.