W.c. Heraeus Gmbh

Heraeus Deutschland Gmbh & Co Kg

Frank Breer

Wolfgang Schmitt

Thomas Krebs

Jurgen Hornung

Karl-Heinz Schaller

Christian Loosz

Joerg Trodler

Jürgen Hornung

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. %.

Solder pastes comprising nonresinous fluxes

Growing community of inventors

Mespelbrunn, Germany

Frank Breer