Church Dwight & Co., Inc.

Eric E Eichhorn

Francis R Cala

Richard A Reynolds

Printing applicators such as metal stencils and screens used to apply solder paste to printed circuit boards are cleaned to remove accumulated solder paste therefrom by an aqueous alkaline salt cleaner. The aqueous cleaner of the present invention comprises alkaline salts such as alkali metal carbonates, a surfactant formulation which contains at least one nonionic surfactant, an alkali metal silicate corrosion inhibitor and stabilizers to maintain the components in aqueous solution. The cleaner of the present invention contains no VOCs and is an effective and safe replacement for alcohol solvents previously used to clean solder paste from screens and stencils.

Aqueous cleaner for removing solder pastes

An aqueous cleaning composition which is capable of removing soldering flux residues, particularly water-soluble flux residues, from a surface of an electronic assembly without leaving significant amounts of white residue on the surfaces of cleaning equipment used in the flux-removal process, contains: (A) a flux-removing portion containing an alkaline salt component composed of at least one potassium salt; and (B) an aqueous portion in which the flux-removing portion is disposed. The composition has a non-potassium alkali metal content of no greater than about 5% by weight. Preferably, the alkaline salt component consists essentially of a potassium salt or mixture of potassium salts, most preferably potassium carbonate or a mixture of potassium carbonate salts. A method of substantially removing soldering flux residues from an electronic assembly surface without leaving significant amounts of white residue on surfaces of cleaning equipment used in the flux-removal method involves applying the aforementioned cleaning composition onto the electronic assembly surface for a period of time sufficient to substantially saponify the flux residues so as to form saponified flux residues, and then removing the saponified flux residues from the electronic assembly surface.

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Princeton, NJ, United States of America

Eric E Eichhorn