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AssigneeInternational Business Machines Corporation
InventorsKrishna G. Sachdev, John T. Butler, Michael E. Cropp, Donald W. DiAngelo, John F. Harmuth, James N. Humenik, John U. Knickerbocker, Daniel S. Mackin, Glenn A. Pomerantz, David E. Speed, Candace A. Sullivan, Bruce E. Tripp, James C. Utter
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This invention relates to the cleaning of objects that relate to semiconductor printing, such as, for example, screening masks. This invention is basically directed to removing, for example, an organic polymer-metal composite paste from screening masks used in printing conductive metal patterns onto ceramic green sheets in the fabrication of semiconductor packaging substrates. More particularly, this invention is concerned with the automated in-line cleaning of paste screening masks with an aqueous alkaline solution of a quaternary ammonium hydroxide as a more environmentally friendly alternative to non-aqueous organic solvents-based cleaning in screening operations for the production multilayer ceramic (MLC) substrates.
An aqueous cleaning method for cleaning paste residue from at least one screening object comprising the use of an aqueous quaternary ammonium hydroxide alkaline solution consisting essentially of at least about 0.3% by weight and at most 2% by weight a member of the group consisting of quaternary ammonia hydroxides and mixtures thereof.
An aqueous cleaning method for cleaning paste residue from at least one screening object comprising the use of an aqueous quaternary ammonium hydroxide alkaline solution consisting essentially of at least about 0.3% by weight and at most 2% by weight of a member of the group consisting of tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, 2-hydroxyethyl trimethyl ammonium hydroxide, ethyl-trimethyl ammonium hydroxide, tetrabutyl ammonium hydroxide and mixtures thereof.
Dependencies are inferred from the claim text.