The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 19, 1997
Filed:
Jun. 07, 1995
Kiminori Ishido, Tokyo, JP;
Masahiro Yamaguchi, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
The surface protection material for printed circuit boards disclosed is one in which a compound having a benzimidazole derivative as an effective component is adjusted to pH range from 1 to 5 with a salt-forming acid and which is an aqueous solution whose metal content of such a heavy metal as copper, manganese and zinc is not higher than 50 ppm. A copper or copper alloy circuit section surface is brought into contact with the surface protection material aqueous solution, and by using an ion exchange resin or by electrolysis, ions of the heavy metal dissolved out of the circuit section surface due to the contact thereof with the surface protection material aqueous solution are removed. The concentration of the heavy metal in the surface protection material aqueous solution is held within 50 ppm. A surface protection film is formed only on the element mounting pad without being formed on a gold plating layer on a terminal, and this enhances the contact reliability of circuits.