Phase field study on the effect of roughness on interfacial intermetallic compounds of micro-solder joints under multifield coupling

Abstract

In order to investigate the influence of roughness on the evolution of interfacial intermetallic compounds (IMCs) and stress states at the micro-solder joints under the strongly coupled thermo-mechanical-electric diffusion, the two-dimensional model of the rough interface for the Cu/Sn/Cu sandwich micro-solder joints was established using phase field method. Parameter A as the evaluation parameter of the interface roughness was used to represent the contour arithmetic mean deviation Ra. The evolutions of the average thickness of the interfacial IMCs and stress distribution at the Cu/Sn/Cu micro-solder joints were investigated with the variation of A. The thickness of interfacial IMCs in anode reached its maximum when A was 0, while obtained the minimum when A was 9. In cathode, the average thickness of the interfacial IMCs at A = 0 was thicker than that at A = 1, 3, 5, but thinner than that at A = 7 and 9. In other words, the growth of the interfacial IMCs was inhibited by the interface roughness in anode. While in cathode, the interfacial roughness inhibited the growth of the interfacial IMCs when 0 ≤ A ≤ 5, but promoted the growth of the interfacial IMCs when 7 ≤ A ≤ 9.