Quasi In Situ Study on the Slipping Behavior and Residual Stress of Copper Strip

Abstract

The preparation method of integrated circuit lead frames has transitioned from stamping to etching, rendering them more sensitive to residual stress. Consequently, the dimensional deviations caused by residual stress become more pronounced, necessitating a thorough investigation into the copper strip processing process, particularly considering the high-precision requirements of the lead frame. A quasi in situ method was employed to monitor the deformation process, and quantitative analyses and graphical reconstructions of the residual stress were conducted. The results indicated that the orientation evolution did not exhibit a significant correlation with grain size or grain aspect ratio. However, the stored energy of the different grains was related to their orientations. Further analysis of slip traces revealed that single or multiple slipping may be activated in grain subdivisions, and the Schmid factor difference ratio (SFDR) value proved to be an effective tool for analyzing this deformation mode. An even more interesting finding was that the deformation mode directly affected the residual stress distribution in local regions. The relationship between residual stress, Schmid factor, and SFDR was further analyzed, and a clear correlation between SFDR and residual stress was found in this study.