Abstract
Recent sophisticated IC's having high-density and super-multiple pins are highly heat sensitive. Such IC's have to be soldered by a localized heat source, separately from other soldered components. This paper describes a new YAG laser soldering system composed of a YAG laser, a fiber and a rectangular robot. The robot supplies paste solder, positions a flat package IC and moves the optical fiber for transmitting YAG laser light to the spots to be soldered.
Experimental results are: 1) The accuracy of pin positions for a 100-pin flat package IC was within ±90μm and in good conformity with calculation; 2) Continuous supply of paste solder was enough to obtain good laser solderabilities; 3) Pre-heating relieved these good solderability conditions; 4) Peel-off strength test of soldered flat package IC leads showed that the adhesion strength between the glass-epoxy resin and thin copper foil wasn't weakened by laser irradiation, and the strength of laser soldered portion exceeded this adhesion strength. About 200 pieces of, heat-sensitive flat package IC's which were not considered to be durable under a conventional soldering system were soldered by this system without any damage.
