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:
Nov. 07, 1995
Filed:
Sep. 02, 1994
Tomoo Murakami, Tokyo, JP;
Takanori Tsunoda, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A fabrication method of a printed wiring board in which the halation effect of light irradiated to a solder resist film is utilized in a process of selectively removing the solder resist film. After a conductive layer is patterned to a given circuit pattern including soldering pads, the solder resist film is formed on the base material to cover the patterned conductive layer. The solder resist film is selectively exposed to light utilizing reflection of the irradiated light from the insulating base material and developed so that the solder resist film is selectively left in areas adjacent to the respective soldering pads. Then, an etching resist film is formed to cover the patterned conductive layer except for the soldering pads, and surface areas of the respective soldering pads are selectively etched using the etching resist film as a mask to produce solder resist dams made of the solder resist film left on the base material. Solder films are formed on the respective soldering pads thus selectively etched. Electronic components can be soldered on the soldering pads with satisfactory reliability even if the soldering pads have narrow pitches such as 500 .mu.m or less.