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

Abstract

In this work, tensile creep tests for Sn-1.0Ag-0.5Cu-0.02Ni solder have been conducted at various temperatures and stress levels to determine its creep properties. The effects of stress level and temperature on creep strain rate were investigated. Creep constitutive models (such as the simple power-law model, hyperbolic sine model, double power-law model, and exponential model) have been reviewed, and the material constants of each model have been determined based on experimental results. The stress exponent and creep activation energy have been studied and compared with other researchers' results. These four creep constitutive models established in this paper were then implemented into a user-defined subroutine in the ANSYSä finite-element analysis software to investigate the creep behavior of Sn-1.0Ag-0.5Cu-0.02Ni solder joints of thin fine-pitch ball grid array (TFBGA) packages for the purpose of model comparison and application. Similar simulation results of creep strain and creep strain energy density were achieved when using the different creep constitutive models, indicating that the creep models are consistent and accurate.

Creep Behavior of 95.8Sn–3.5Ag–0.7Cu Solder Joints, and a Modified Constitutive Model for the Joints

“…Therefore, it might be concluded that, at higher creep strain rate, brittle fracture is prone to occur near the solder/IMC interface. Our results also reveal that the creep strain rate ranges from 10 À9 s À1 to 10 À2 s À1 when the shear stress increases from 2-26 MPa at three different test temperatures, similar to results obtained by Chen et al 2 Log-log plots of creep strain rate c as a function of modulus compensated shear stress ( s G ) of shear-lap solder joints at three different test temperatures are shown in Fig. 12.…”

Mechanical Response of Cu/Sn58Bi-xNi/Cu Micro Solder Joint with High Temperatures

“…By comparison, the addition of Ni elements in the micro solder joints exhibits smaller creep displacement at high temperatures and a better creep resistance. Research has shown that Ni can refine the microstructure in the solder alloy, and Ni 3 Sn 4 IMC particles formed in the alloy; therefore, it can increase the resistance to dislocation, which improves the creep properties [34][35][36]. In addition, it can be seen from Figure 6 that the creep displacement increases with the increase of temperature.…”

Physical properties of Sn58Bi–xNi lead-free solder and its interfacial reaction with copper substrate

“…3(a), Sn58Bi was composed of eutectic structure, where the dark and light phases were respectively Sn-rich and Bi-rich phases. On the whole specimen, the lamella structure of Sn58Bi became refined with the addition of Ni, a phenomenon which was attributable to the increase of nucleation sites during solidification in response to the introduction of Ni [26,27]. The intermetallic phase of Ni 3 Sn 4 appeared as a dark rod and was randomly oriented in the Sn58Bi matrix.…”