The interfacial Cu–Sn intermetallic compounds (IMCs) growth behavior of Cu/Sn/Cu sandwich structure via induction heating method

Abstract

Forming full IMC solder joint technology has become one of the leading candidates to replace conventional high temperature Pb-based solder for wide bandgap (WBG) power modules (SiC and GaN) due to its excellent thermo-stability and high electrical/thermal conductivity. Few studies were investigated the formation and growth mechanism of interfacial Cu–Sn IMCs layer of Cu/Sn(10 μm)/Cu system during induction heating method. The results showed that the growth behavior of Cu–Sn IMCs of the Cu/Sn interface by induction heating method was different from Cu–Sn IMCs growth behavior of the Cu/Sn interface by conventional soldering method. The Cu6Sn5 thickness increased by Cu/Sn solid–liquid interfacial reaction before the bonding time of 45 s and then decreased by Cu6Sn5/Cu solid–solid interfacial reaction within the bonding time of 60 s. The Cu3Sn thickness increased by solid Cu/liquid Sn interfacial reaction and solid Cu6Sn5/solid Cu interfacial reaction within the bonding time of 60 s. A formation mechanism model of Cu–Sn compounds was also presented. The mathematic model of Cu layer consumption at different temperature was also illustrated, which indicated that higher temperature is in favor of the consumption of Cu layer. By knowing the relationship between the thickness of Cu layer on SiC power device at different temperature could be designed when evaluating the reliability of device by induction heating process.