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An Inspection Aid for Drilled Holes

IP.com Disclosure Number: IPCOM000038021D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Adiano, CA: AUTHOR [+2]

Abstract

Printed Circuit Boards have over a thousand drilled holes to be inspected. A tool is described which improves the inspection techniques.

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An Inspection Aid for Drilled Holes

Printed Circuit Boards have over a thousand drilled holes to be inspected. A tool is described which improves the inspection techniques.

Printed Circuit Boards have thousands of drilled holes that must be inspected for A) location B) size C) missing or extra holes. These drilled holes are often no larger than 0.018 inch diameter with tolerances of 0.003 inch. This tool will improve inspection techniques.

The Aid consists of several parts, some of which must be produced with very tight accuracy and tolerances. 1. Front Template - transparent yellow background with transparent clear circles in the same pattern as drilled holes. The diameter of the circles is equal to drilled hole diameter location tolerance. 2. Back Template - transparent clear background with opaque black circles matching the drilled hole pattern. The diameter of the black circles is equal to the drilled hole diameter location tolerance. 3. Green Back light.

4. Magnifying inspection glass.

The operation is as follows:

The drilled panel is placed between the Front and Back

Templates with a green backlight. The drill defects are easier to see; 1. Missing holes - show as copper colored circles in the clear portions of yellow template. 2. Extra holes - show as blue circles.

3. Incorrect hole sizes - show as unusually large or unusually small circles in clear portions of yellow front template. 4. Misregistered [off-location] holes - show as blue portions of circles i...