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US 5,556,023 AGranted
Method of forming solder film
AssigneeShowa Denko K.K.
InventorsTakeo Kuramoto, Masataka Watabe, Satoshi Noda, Takashi Shoji, Takekazu Sakai
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Abstract
A method is available for forming a solder film on a metallic surface such as a pad of a metallic circuit of a printed circuit board and a lead frame of electronic parts which is capable of forming a precise and fine pattern. The method comprises selectively imparting tackiness to only a predetermined part of the metallic surface by use of a tacky layer-forming solution, adhering a powdered solder to the resulting tacky part, and then melting the solder by heating to thereby form a solder film.
Claims7
A method of forming a solder film which comprises the steps of:
- i. contacting the entire surface of an article with a tacky layer-forming solution;
- wherein said article comprises exposed predetermined areas of metallic surface, and said tacky layer-forming solution comprises at least one compound selected from the group consisting of benzotriazole derivatives, naphthotriazole derivatives, imidazole derivatives, benzoimidazole derivatives, mercaptobenzothiazole derivatives, benzothiazole thiofatty acid derivatives, and triazine derivatives;
- ii. imparting tackiness to only said exposed predetermined areas of metallic surface by means of a chemical reaction between said tacky layer-forming solution and the metal in said exposed predetermined areas of metallic surface,
- iii. adhering a powdered solder to the resulting tacky part;
- and
- iv. melting the solder by heating to thereby form a solder film.
3 more elements
Dependencies are inferred from the claim text.