Influence of the structure of blanked materials upon the blanking quality of copper alloys

Abstract

Improving of the productivity of the blanking industry of leadframes (supports for electronic components) involves several research areas. The blanking ability of copper alloys is the topic of this study. In this paper, we propose to determine the influential parameters of blanked materials with respect to the facies of blanked profiles. For this purpose, the blanking tests on usual copper alloys as well as original alloys, in particular, in terms of microstructure, enabled us to show that the blanking profile was strongly influenced by the mechanical characteristics and the microstructure of the alloys. As a matter of fact, the more work hardened those are (depending upon the making process of the sheet), the larger the fracture zone, is for its own leading to a weaker sheared zone, detrimental as for to the overall blanking quality. The burr resulting from blanking, it is only conditioned by the microstructure and, in particular, by the precipitates present in the copper matrix. Its formation is not influenced by the rate of work hardening. As for the roll-over zone, it depends mainly on the blanking geometry (punch/die clearance).