Method of and apparatus for inspecting the minimum annular width of a land on a printed circuit board
US5408538A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 1, 1994 |
| Grant date | Apr 18, 1995 |
| Priority date | — |
| Expiry date | Aug 1, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/30141
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A printed pattern is provided with a wiring pattern having a land and a through hole surrounded by the land. The wiring pattern and the through hole are read by a photoelectric image sensor to obtain a pattern image and a hole image, respectively. A pattern gauge image is defined by the pattern image, and a hole gauge image having a ring-like shape is obtained from the hole image. A logical product between the inversion image of the pattern gauge image and the hole gauge signal provides a protrusion region image. Since the hole gauge image has an isotropic contour, the minimum annular width of the land is detected, independent of the direction in which the through hole is deviated from the land.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.