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:
Jul. 30, 1991
Filed:
Aug. 06, 1990
Takashi Haruta, Amagasaki, JP;
Takaharu Nagano, Amagasaki, JP;
Takeyoshi Kishimoto, Yamatokoriyama, JP;
Yasushi Yamada, Osaka, JP;
Tomoko Yuno, Suita, JP;
MEC Co., Ltd., Hyogo, JP;
Abstract
Disclosed is a method for removing a layer of tin or tin-lead alloy from a copper substrate of a printed circuit board employing the two different reagents in a two-step procedure without damaging the substrate, and at the same time, preventing formation of whitish precipitates in the treating solution. In the first step, the layer of tin or tin-lead alloy is selectively removed with the first reagent having a comparatively mild oxidation capability, then in the second step the intermetallic layer consisting of tin and copper is removed with the second reagent having a comparatively strong oxidation capability. This process ensures a smooth and effective operation in the production of high quality printed circuit boards.