During processing and qualification, packages are subjected to significant temperature changes. A thermal cycling test is commonly applied for reliability qualification to determine the ability of components and interconnects to withstand mechanical stresses induced. Thermal oxidation of metal surfaces, especially on copper leadframe, is unavoidable. This study investigates delamination between Epoxy Molding Compound (EMC) and copper lead frame using the button shear test and the X-ray Photoelectron Spectroscopy (XPS) technique. The button shear samples were subjected to thermal cycling following JEDEC standards. The shear test was conducted on the model after the thermal cycling. After molding, a thin copper oxide film is formed on the leadframe across the EMC-leadframe interface. Other investigators have investigated the change in adhesion between the oxide film and EMC as a function of the copper oxide’s thickness and chemical content. The oxide thickness in the samples was skinny and did not reach the critical value reported in previous studies. The XPS technique examines the chemical composition after the shear test showing only cuprous oxide at the entire interfacial area.
In contrast, cuprous and cupric oxides were observed in other sample regions. The button shear test results showed an increase in critical shear force at the initial phase of the thermal cycling test, followed by a gradual fall in value. The increase in shear pressure indicates that chemical and mechanical factors are significant in thermal cycling. After analyzing the button shear and XPS results, a linear relationship is found between the cuprous oxide content and the adhesion force. This leads to the observation that the change in interfacial adhesion is related to the growth of cuprous oxide content on the lead frame. If you are looking for high quality, high purity, and cost-effective copper oxide, or if you require the latest price of copper oxide, please feel free to email contact mis-asia.
