A New Creep Constitutive Model for Eutectic Solder Alloy

Abstract

In this study, a large number of creep tests were carried out to study the effect of stress level and testing temperature on the creep behavior of 63 Sn/37Pb solder in a systematic manner. Based on the dislocation controlled creep mechanism and Gibbs’ free-energy theory, a new creep constitutive model was proposed. The model was found to describe accurately the creep flow of the solder and to be capable of explaining the issues of stress and temperature dependent stress exponent and activation energy in the Arrhenius power-law creep model. Furthermore, the model was employed to predict accurately the long-term reliability of solder joints in a PBGA assembly.

Creep Properties of Sn-1.0Ag-0.5Cu Lead-Free Solder with Ni Addition

“…The stress exponent decreases with increasing temperature for both high and low stress ranges. This stress exponent finding is consistent with other researchers' results, such as those of He et al 23 for Sn-3.0Ag-0.5Cu-xBi solders, Shi et al 35 for 63Sn-37Pb solder, Shi et al 36 for Sn-0.7Cu solder, and Xiao et al 32 for Sn-3.9Ag-0.6Cu solder. …”

“…The minimum rate was taken as the creep strain rate of the steadystate creep stage. 35 The creep strain rate is dependent on the creep stress level and the test temperature. Figure 4 shows the effect of temperature on the creep curve of the solder at a certain creep stress level.…”

“…Pang et al 38 studied bulk solder and solder joint properties for Sn-3.8Ag-0.7Cu solder and showed that the equivalent yield stress and ultimate tensile strength (UTS) exhibit good agreement between bulk solder and solder joint test results. Shi et al 35 applied a creep constitutive model developed for bulk 63Sn-37Pb solder alloy to plastic ball grid array (PBGA) solder joints by FEA simulation and achieved an accurate solder joint fatigue life prediction compared with testing life. Wang et al 39 successfully applied the viscoplastic and creep models from bulk solder to study the stress-strain behavior of solder joints at package level.…”

Creep failure mechanism and life prediction of lead-free solder joint

“…There so many papers focus on the visco-plastic behavior of solder or solder joint [2][3][4][5][6][7][8][9][10][11]. Results achieved from different authors have a little scatter, which may attribute to the difference between the fabrication of samples, or the loading condition.…”

Advances in High-Power Laser Diode Packaging

“…The solder material will experience high creep deformation, which implies a reliability concern for these solder joints. Hence, bonding of laser diodes using soft solder will face reliability problems (Shi et al, 2000(Shi et al, , 2002. The reliability of the joint is a critical issue for the practical design and fabrication of a mechanically stable and reliable assembly.…”