Abstract
This study describes temperature difference reduction among solder balls when solder balls are heated up with a uniform laser beam at a time by using CFD analysis. We focus on flexible printed wiring board. First, we detected the reason why temperature of each solder ball becomes different. Then, to reduce temperature difference, we designed light shielding mask. As a result, by using light shielding mask, temperature difference among solder balls can be reduced. Further, it can be concluded that heat diffusion through copper wires on the board is key point to design the mask.
