Temperature Dependent Micromechanical Testing on the Formation of Cu/Sn Intermetallic Thin Films

Abstract

A temperature controlled tensile testing was performed to investigate the influence of external stress on the growth of an interfacial Cu-Sn IMC layer. The test specimens were prepared by depositing 25 μm layers of tin atop of copper substrate using electroplating. Samples were then clamped in a micromechanical testing apparatus integrated with a furnace. Experiments were carried out using load feedback control to provide constant load on the specimens with the stress level of 50, 100 and 150 MPa under constant temperature at 200 °C for 3–5 h annealing. Comparisons were made between samples undergoing stresses and those without stresses annealing. We observed the influence of stress levels and aging time on the formation of intermetallic compounds (IMC). Stress does influence the formation of Cu/Sn IMC. The thickness of IMC increased under stress. The growth rate of IMC was faster in stressed tin samples. Moreover, the formation of IMC micrographic structures under external stress differs considerably according to the level of stress.