Mechanism of Cutting Temperature Rise in Micro Drilling on Printed Wiring Boards

Abstract

This paper describes the mechanism of cutting temperature rise in micro drilling on Printed Wiring Boards (PWBs), which affects the micro-drilled hole wall quality. The drill temperature monitored by a thermography was evaluated in drilling. Moreover, we investigated the influence of drill workload, which was calculated with cutting force measured by a dynamometer, on the drill temperature. The following conclusions were reached: (1) The drill temperature tends to increase with the drill workload caused by frictional torque between hole wall and the land or margin of drill. (2) The frictional torque increases with the spring back of drilled hole wall in drilling. The spring back of drilled hole wall increases with the outer corner wear of drill cutting edge in drilling. (3) The reduction of the workload by the friction seems to be effective in order to obtain the high quality micro-drilled hole wall.