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:
Jun. 05, 1990
Filed:
Jun. 22, 1988
Yasuhiko Hara, Machida, JP;
Kenzo Endo, Hadano, JP;
Hitachi Ltd., Tokyo, JP;
Abstract
A method and apparatus for detecting through-hole voids in a multi-layer printed circuit board. The through-hole is formed with an electrical conductor for interconnecting wiring patterns of upper layers and wiring patterns of lower layers of the printed wiring board and is illuminated with a beam having a wavelength falling within a specified wavelength band capable of exciting an luminescent beam from a layer material. The layer material is exposed by a through-hole void in the through-hole of the printed wiring board. The luminescent beam excited by the illumination beam impinging upon the layer material by way of the through-hole void in the through-hole is focussed by means of a focussing optical system and a photoelectric converter. The photoelectric converter converts the luminescent beam into an electrical signal. The presence of a through-hole void is indicated by the electrical signal.