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:
Apr. 28, 1998
Filed:
Jul. 25, 1996
Fujitsu Automation Limited, Kawasaki, JP;
Abstract
For a print-circuit board 10 of a good product, probes 31 and 32 are made to be electrically continuous with a ground plate 13 and a wiring pattern i respectively to measure a capacitance Cgi, which is then stored in a storage device 44. A capacitance Ci of a print-circuit board 10, the object of testing, is measured in a similar manner and a ratio .mu.=(average value Ca of a several measured capacitance value of the object of testing/(average value Cga of the corresponding measured capacitance values of the good product) is calculated. If Ci<Cgj(1-.DELTA.e0) or Ci>Cgj(1+.DELTA.e0), the measured capacitance values Ci and Cgjare excluded from the objects of calculation of the average values. If Cj<.mu..Cgj(1-.DELTA.e) or Cj>.mu..Cgj(1+.DELTA.e), a wiring j is judged to be defective and the resistance measuring method is employed to judge the details of the defect. The tolerance rate .DELTA.e0 and .DELTA.e are 0.15 and 0.02 respectively.