Development of the Fine Tool Processing for Fine Pitch Lead Frames and Its FEM Analysis

Abstract

Process capability for the fine tool processing was studied and the FEM analysis was done in order to clarify the tool strength demanded at the stamping. It was confirmed that the die inserts and the punches could be processed to 77μm in space and 74μm in thickness respectively by wire electric discharge and grinding machines. The process accuracy of die inserts processed by wire electric discharge machine using a wire of φ40μm diameter was determined. The process accuracy of punches processed by two different methods was found to depend on the processing. The effects of the curvature, fixing position and bending shape on the punches buckling strength were clarified by the FEM analysis. The results of the FEM analysis also showed that variations in the widths and step heights of die holes reduce the die inserts strength for the multipin shearing model.