Effect of 0.05 wt.% Pr Addition on Microstructure and Shear Strength of Sn-0.3Ag-0.7Cu/Cu Solder Joint during the Thermal Aging Process

Abstract

The evolution of interfacial morphology and shear strengths of the joints soldered with Sn-0.3Ag-0.7Cu (SAC0307) and SAC0307-0.05Pr aged at 150 • C for different times (h; up to 840 h) were investigated. The experiments showed the electronic joint soldered with SAC0307-0.05Pr has a much higher shear strength than that soldered with SAC0307 after each period of the aging process. This contributes to the doping of Pr atoms, "vitamins in alloys", which tend to be adsorbed on the grain surface of interfacial Cu6Sn5 IMCs, inhibiting the growth of IMCs. Theoretical analysis indicates that doping 0.05 wt.% Pr can evidently lower the growth constant of Cu6Sn5 (DCu6), while the growth constant of Cu3Sn (DCu3) decreased slightly. In addition, the electronic joint soldered with SAC0307-0.05Pr still has better ductility than that soldered with SAC0307, even after a 840-h aging process.

The Enhanced Mechanism of 0.05 wt. % Nd Addition on High Temperature Reliability of Sn-3.8Ag-0.7Cu/Cu Solder Joint

“…Generally, the growth of interfacial IMC layer is controlled by atom diffusion. The relationship between the thickness of interfacial IMC layer and aging time coincides with the following diffusion formula [13]:…”

“…It has been reported that the RE elements with high chemical activity could have beneficial impacts on refining the microstructure of solder as well as inhibiting the growth of interfacial IMCs [13,14]. Sadiq et al [15] added trace amount of RE La into Sn-Ag-Cu alloy and investigated its high-temperature reliability (150 • C).…”