Flux-Less Solder Ball Attachment Technology (FLAT) for Advanced BGA Assembly

Mass reflow soldering technology using flux have been widely adopted in semiconductor assembly process for decades, particularly in ball grid array (BGA) solder ball attachment process. However, advanced semiconductor packages are now facing interconnect scaling down to sub-micron levels, with the pitches of both bumps and BGAs becoming increasingly finer. Simultaneously, dies are becoming larger and thinner, while PCB boards are also increasing in size and becoming thinner. These changes have made it a significant challenge to control flux residue and die/PCB board warpage, which can impact reliability after mass reflow soldering.