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AssigneeW.C. Heraeus GmbH
InventorsWolfgang Schmitt, Christian Loosz, Frank Breer, Jürgen Hornung, Thomas Krebs, Joerg Trodler
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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. %.
1-10. (canceled)
A storage-stable gel containing as main components a carboxylic acid component, an amine component, and a solvent component, wherein the carboxylic acid component is a thermally easily removable substance and comprises at least one carboxylic acid, the amine component is a thermally easily removable substance and comprises at least one tertiary amine, and the solvent component comprises at least one polar solvent.
A method for production of a gel, the method comprising gelling with each other a carboxylic acid component, an amine component, and a solvent component, wherein the carboxylic acid component is a thermally easily removable substance and comprises at least one carboxylic acid, the amine component is a thermally easily removable substance and comprises at least one tertiary amine, and the solvent comprises at least one polar solvent.
A solder paste comprising a soft solder powder dispersed in a gel, wherein the gel comprises essentially a carboxylic acid component and an amine component, the components being gelled in a polar solvent.
A method for soldering components and subsequent bonding, the method comprising remelting a solder paste for attachment of a component, and then bonding the component without further cleaning of bonding surfaces with surface active or basic substances.
Dependencies are inferred from the claim text.