Phase transformation and fracture behavior of Cu/In/Cu joints formed by solid-liquid interdiffusion bonding

摘要

In this paper, microstructure evolution and phase transformation of Cu-In intermetallic compounds in Cu/In/Cu joints formed by solid-liquid interdiffusion bonding at 260 and 360 ℃ were investigated respectively. The shearing properties and fracture behaviors of the Cu/ In/Cu joints formed under different bonding conditions were also studied. For Cu/In/Cu joints bonded at 260 ℃, Cu_(11)In_9 phase firstly generated and then Cu_2In phase formed between Cu_(11)In_9 layer and Cu substrate. For Cu/In/ Cu joints bonded at 360 ℃, Cu_2In phase firstly formed and then parts of Cu_2In grains transformed to Cu_7In_3 phase, and this transition from incomplete to complete coverage of Cu_2In/Cu_2In grain boundaries by Cu_7In_3 phases was observed with the bonding time increasing. The shear test results show that Cu_2In was high-quality phase which could improve the mechanical properties of Cu/In/Cu joints. After shear test, the fractures in Cu/In/Cu joints bonded at 260 ℃ were found at Cu_(11)In_9 layers and the fracture mode was cleavage fracture. In the case of the joints bonded at 360 ℃, the intergranular fractures were found at the interface between Cu_2In layer and Cu_7In_3 layer while the cleavage fractures were found at Cu_7In_3 layer.