FLIP CHIP INTERCONNECTION USING NO-CLEAN FLUX

摘要

A FLUX CHIP METHOD OF JOINING A CHIP (325) AND A SUBSTRATE (315) IS DESCRIBED. A THERMO-COMPRESSION BONDER IS UTILIZED TO ALIGN THE CHIP (325) AND SUBSTRATE (315) AND APPLY A CONTACT FORCE TO HOLD SOLDER BUMPS (305) OF THE SUBSTRATE (315) AGAINST METAL BUMPS (325) ON THE CHIP. THE CHIP (325) IS RAPIDLY HEATED FROM ITS NON-NATIVE SIDE BY A PULSE HEATER IN THE HEAD OF THE BONDER UNTIL THE RE-FLOW TEMPERATURE OF THE SOLDER BUMPS (305) IS REACHED. PROXIMATE WITH REACHING THE REFLOW TEMPERATURE AT THE SOLDER BUMPS (305), THE CONTACT FORCE IS RELEASED. THE SOLDER IS HELD ABOVE ITS RE-FLOW TEMPERATURE FOR SEVERAL SECONDS TO FACILITATE WETTING OF THE SUBSTRATE'S METAL PROTRUSIONS AND JOINING. A NO-CLEAN FLUX (405) THAT HAS A VOLATILIZATION TEMPERATURE BELOW THE MELTING POINT OF THE SOLDER BUMPS (305) IS UTILIZED TO MINIMIZE OR ELIMINATE THE NEED FOR A POST INTERCONNECTION DE-FLUX OPERATION. FIG. 2