Laser soldering for chip-on-glass flat panel display application mounting in

Abstract

Chip-on-glass (COG) mounting of area array electronic packages was attempted by heating the rear surface of a contact pad film deposited on a glass substrate. The pads consisted of an adhesion (i.e., Cr or Ti) and a top coating layer (i.e., Ni or Cu) was heated by an UV laser beam transmitted through the glass substrate. The laser energy absorbed on the pad raised the temperature of a solder ball which was in physical contact with the pad, forming are flowed solder bump. The effects of the adhesion and top coating layer on the laser reflow soldering were studied by measuring the temperature profile of the ball during the laser heating process. The results were discussed based on the measurement of reflectivity of the adhesion layer. In addition, the microstructures of solder bumps and their mechanical properties were examined.