Title :
Laser removal of molded flashes from a leadframe heatsink surface
Author :
Zheng, Hongyu ; Chen, Qiong ; Tan, J.L. ; Lim, G.C.
Author_Institution :
Machining Technol. Group, Singapore Inst. of Manuf. Technol., Singapore
fDate :
4/1/2005 12:00:00 AM
Abstract :
Epoxy residues on a leadframe heatsink surface of a molded integrated circuit package are a major concern for the subsequent solder plating process. Studies using a pulsed green laser to remove the epoxy residues from precoated copper-based leadframes were carried out. Effects of the laser beam mode profile and process variables on the effectiveness of residue removal and surface morphology of the heatsink were investigated. Ring marks that appeared on the laser-irradiated area were analyzed by secondary ion mass spectroscopy to determine the depth profiles of the layered structures. Calculations were carried out to estimate the temperature rise in the surface due to the laser irradiation. It is concluded that laser deflashing can be a process suitable for production uses.
Keywords :
heat sinks; integrated circuit packaging; laser materials processing; solders; surface morphology; copper-based lead-frames; epoxy residues; etching; laser beam mode profile; laser cleaning; laser decapping; laser deflashing; laser irradiation; laser removal; layered structures; leadframe heatsink surface; molded flashes; molded integrated circuit package; pulsed green laser; secondary ion mass spectroscopy; solder plating process; surface morphology; Integrated circuit packaging; Laser beams; Laser modes; Lead; Mass spectroscopy; Optical pulses; Ring lasers; Surface emitting lasers; Surface morphology; Temperature; Etching; laser cleaning; laser decapping; laser deflash;
Journal_Title :
Electronics Packaging Manufacturing, IEEE Transactions on
DOI :
10.1109/TEPM.2005.846833
