The surface modification of substrate for roughness improvement

For assembly process, materials are important like substrate, bump type, UF type. etc. We focus on the surface of substrate in this research. The surface is one of the key factors to widen the process window with same process condition. Roughness will impact the flowing capability of UF dispensing and adhesion. It may cause void issue, poor adhesion and reliability fail. In this study, plasma and descum condition are studied for surface modification of solder mask on substrate; plasma and flux clean times were used to verify the change of surface in assembly process. In order to define the roughness properties, laser microscope, contact angle machine and SEM were used to identify the value of roughness, contact angle and morphology. After plasma process, the roughness has no significant different for all candidates. With flux clean process, it can be improved about 15 similar to 37%.