Fracture toughness of lead-free solder joint as a function of geometric parameters

Recently, electronic boards are widely used in various devices such as cell phones, laptops, automobile manufacturing, medical industry. Various strain rates from quasi-static to drop loading condition are subject to electronic products. Any failure in microelectronicinterconnections in electronic devices can cause power outage and/or overall failure of the device. Therefore, it is useful to consider the fracture behavior of these interconnections. This helps to improve prediction of the reliability of electronic devices. In this study, the effect of geometric parameters such as bond-line width, bond-line thickness and adherend thickness on the fracture behaviorof lead-free solder joints were investigated. Fracture tests were performed on copper-SAC305-copper using double cantilever beam (DCB) specimen under mode I loading condition at a strain rate of 0.03 s-1. A finite element model (FEM) was then used to calculate the critical strain energy release rate, Jci from the measured fracture load. The result showed that the variation in bond-line widthfrom 8mm to 21mm does not have significant effect on the fracture behavior. Changes in bond-line thickness from 150μm to 450μm increased the fracture force while fracture energy remained almost unchanged. The effect of adherend thickness on Jci was found to be significant (Jci decreases with increasing adherend thickness).Therefore, it could be concluded that the copper adherends changedthe level of constraint applied on the joint deformation.

کلیدواژه ها:

fracture behavior ، solder joint ، geometric parameters ، critical strain energy release rate