Effect of Tool Wear on Force and Quality in Dam-Bar Cutting of Integrated Circuit Packages

Abstract

Dam-bar cutting is an essential trimming process in which the dam-bars in between the leads of Integrated Circuit (IC) packages are removed after encapsulation and deflashing. There are stringent requirements imposed on the quality of the sheared dam-bar edges so as to avoid the post-process failure of the package during assembly on to printed circuit boards. In this paper, a detailed analysis of the wear characteristics of the dam-bar cutting tools and their effects on the force and quality of dam-bar cutting process is reported. The correlation between the peak dam-bar cutting force and the tool wear was also studied under various combinations of wear states of the punch and die. Based on the experimental findings, relationships have been built to correlate the states of wear of the punch and die to the protrusion and burr height of the dam-bar sheared edge. Hence, revised tool life criteria were proposed for the quality control of dam-bar cutting process. The results of the analysis provide an important means for the on-line monitoring of tool wear and edge quality of dam-bar cutting process in the IC packaging industry.