Development of single-point laser bonding process for TCP outer-lead-bonding

Tape-Carrier Package (TCP) is characterized by its thinness and heat radiating ability, and is one of the major IC packaging technology. In this paper, a single point TCP bonding process using a YAG laser is proposed. The proposed bonding process is made by soldering each lead lightly held down by a needle-like tool one by one. The single point bonding is an effective bonding system to eliminate problems of the most popular method, the gang-bonding, in the sense that the bonding parameters can be selected for each lead properly. The YAG laser was selected as the heat source for the quick soldering. Two key developments were made to realize this concept: the stabilization of the laser power fluctuation which makes the soldering condition unstable; and the development of a laser system for soldering. The laser power fluctuation was stabilized applying the real-time feed-back control technique.