SOLDER PASTES WITH RESIN-FREE FLUXING AGENT

摘要

ACCORDING TO THE INVENTION, A RESIN-FREE SOLDER PASTE MADE FROM A METAL POWDER, PARTICULARLY SOFT SOLDER AND A GEL, IS PREPARED, WHEREIN THE GEL ACCORDING TO THE INVENTION LEAVES NO RESIDUE ON THE METAL SURFACE DURING THE REMELTING OF THE METAL POWDER. THE GEL ACCORDING TO THE INVENTION IS BASED ON A MIXTURE THAT IS STABLE DURING STORAGE AND THAT COMPRISES CARBOXYLIC ACID(S), AMINE(S), AND SOLVENT(S). IMPORTANT USES ARE THE APPLICATION OF SOFT SOLDER PASTES ON POWER-MODULES, DIE-ATTACH, CHIP-ON-BOARD, SIP (SYSTEM-IN-PACKAGE), FOR WAFER-BUMPING, PARTICULARLY ON UBM'S (UNDER-BUMP-METALLIZATION), AND SMT (SURFACE MOUNTED TECHNOLOGY), PARTICULARLY COATED CIRCUITS. WITH THE USE OF RESIN-FREE SOFT SOLDER PASTES ACCORDING TO THE INVENTION, CLEANING IS ELIMINATED BEFORE A PROTECTIVE COATING PROCESS AFTER THE SOLDERING OF AN ELECTRICAL CONNECTION, AND THE FORMATION OF PORES IN SOLDER BUMPS DEPOSITED ON UBM'S IS REDUCED TO LESS THAN 20 VOL.%.