The fast formation of Cu-Sn intermetallic compound in Cu/Sn/Cu system by induction heating process

The fast formation of Cu3Sn in a Cu/Sn(10 mu m)/Cu solder joints were investigated by induction heating process in a few minutes and under a low pressure of 0.01 MPa at ambient temperature. The introducing of induction heating process showed benefit effects on enhancing the interfacial reaction at the liquid Sn/solid Cu metallization interface. From the three-dimensional microstructural observation of interfacial IMCs at different bonding times, scallop-liked Cu6Sn5 was formed while planar-liked Cu3Sn was formed between Cu and Cu6Sn5 at initial soldering stage. After that, the scallop-liked Cu6Sn5 grew with a transition to dendritic-liked morphology while planar-liked Cu3Sn grew with a transition to columnar-liked morphology until the full Cu3Sn solder joint was eventually formed. Accompanying with the movement of Cu atoms in the molten Sn, the morphology of columnar-liked Cu3Sn compounds surrounded by dendritic-liked Cu6Sn5 compounds was formed due to constitutional super-cooling. The rapid microstructure evolution of the interfacial IMCs was caused by the joule heating effect as well as the electromagnetic stirring effect. (C) 2017 Elsevier B.V. All rights reserved.