Effect of the addition of Cu6Sn5 nanoparticles on the growth of intermetallic compounds at the interfaces of Sn3.0Ag0.5Cu solder joints

To solve the issue of overgrowth of intermetallic compounds (IMCs) at the interfaces of solder joints in electronic devices, this study has focused on the modification of Sn3.0Ag0.5Cu (SAC305) solder by adding Cu6Sn5 nano particles (NPs). It was found that Cu6Sn5 NPs would adsorb on the surfaces of the interfacial IMCs due to the high surface energy in solid-liquid reactions and resulted in a peculiarly ordered growth pattern of the new grains. In addition to this, a combined growth mechanism involving encapsulated and engulfed crystal growth of the interfacial IMCs was identified. The addition of Cu6Sn5 NPs was also calculated to increase the activation energy associated with interfacial IMCs growth during high-temperature service, thereby effectively inhibiting the overgrowth of interfacial IMCs. When the mass fraction of Cu6Sn5 NPs was 0.6 wt%, the activation energy for interfacial IMCs growth was the highest (31.9 kJ/mol).