Laser bending of leadframe materials

Over the last decade, there have been numerous research works conducted on laser bending. However, less research effort has been spent on investigating the laser bending of thin sheets using a low power laser. In the present study, a low power Nd:YAG laser is used to experimentally examine the bending behaviour of a thin steel alloy strip which is now being used for integrated circuit leadframes. In the experiments, a machine vision system has been used to measure bending angles in a more accurate and efficient way. The experimental results show that the final bending angle in a multiple-irradiation laser bending process is related strongly to the laser power, the processing velocity, the number of irradiations and the holding time between each laser irradiation. A threshold line energy of about 0.14 J mm(-1) is observed, and a linear relationship between the bending angle and the line energy is found when the latter is below 1 J mm(-1). (C) 1998 Elsevier Science S.A. All rights reserved.