抄録
In die attach process instead of preforms; the need of a new solder paste technology is required, which should operate better in formic acid reduction reflow. This article discusses the development and validation of such solder paste. To achieve such solder paste, a cavity between solder powders in solder paste has been developed by using a special heat resistant agent. A combination of optimized formic acid delivery process and reflow process, formic acid can penetrate deeper into the solder paste by the use of its cavities than conventional pastes. Consequently, wettability towards large surface area with low void rate can be assured as how conventional solder preform acts. In addition, very low flux residue is advantageous which retains heat resistance. Thus, wire bonding and resin molding can be done without cleaning the residue and able to obtain high reliability.
