Modelling the effect of plastic anisotropy on springback of integrated circuit leadframes

Recently, some published experimental results have revealed that springback of some common types of integrated circuit (IC) leadframes in roller forming is highly related to their anisotropic properties. In this paper, a new plane stress bending model based on the approach of Crystallographic Mechanics of Textured Polycrystals (CMTP) has been developed to predict the deformation behaviour and springback of a copper alloy. Based on the texture data obtained from the measured orientation distribution function, springback of the copper alloy in the rolling direction was determined to be greater than that perpendicular to the rolling direction. It was also found that the springback increased with increasing die radius. The predictions were compared to the experimental findings, and the trends of them were in reasonable agreement.