Pre-notch and pre-crack size effects on T-peel fracture behaviors of SAC305 solder joints

T-peel test of ductile adhesive is always an interesting and important topic in peeling mechanics and fracture mechanics. In this paper, the pre-notch and pre-crack effect on the T-peel ductile test with a ductile adhesive layer is studied. Based on the experimental test of SAC 305 adhesive and copper adherent T-peel tests, it is found that the peak loads, fracture toughness, resistance curve, and adhesive toughness are sensitive to pre-crack or pre-notch lengths. Short pre-notch or pre-crack trigger unsteady state debonding frequently, and deep pre-notch or pre-crack conditions achieve steady state debonding more easily. Different data reduction schemes such as simple beam theory (SBT), corrected beam theory (CBT), and compliance-based beam method (CBBM) will lead to variations of fracture toughness extractions for T-peel tests. Trapezoidal shape cohesive zone model (CZM) is found to be better matching T-peel tests conducted in this paper. However, T-peel samples with shorter pre-notch or pre-crack lengths are hard to simulate with the CZM method due to the unstable crack propagation. The reasons may lead to the discrepancy between pre-notch and pre-crack T-peel samples are also presented and discussed. The selection of different pre-notch or pre-crack lengths is a very important factor that needs to be considered in the T-peel test.