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Finding Shorts in Printed Circuit Boards

IP.com Disclosure Number: IPCOM000091070D
Original Publication Date: 1969-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

DeGroat, PM: AUTHOR [+3]

Abstract

The device checks ground planes and voltage planes of doughnut construction found in core sheets to locate hairline shorts which can occur between the ground or voltage plane to doughnut. The device consists of base 10 for mounting and locating circuit pattern board 11 to be tested. Template 12 of a thin insulating, semirigid, self-supporting material is provided which is perforated so as to provide an opening between its top and bottom surface corresponding to the underlying circuit pattern. Template 12 has a nonconductor top side and a conductor bottom side. Conductive brush probe 13 is connected in circuit with short indicator light device 14 and board 11.

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Finding Shorts in Printed Circuit Boards

The device checks ground planes and voltage planes of doughnut construction found in core sheets to locate hairline shorts which can occur between the ground or voltage plane to doughnut. The device consists of base 10 for mounting and locating circuit pattern board 11 to be tested. Template 12 of a thin insulating, semirigid, self-supporting material is provided which is perforated so as to provide an opening between its top and bottom surface corresponding to the underlying circuit pattern. Template 12 has a nonconductor top side and a conductor bottom side. Conductive brush probe 13 is connected in circuit with short indicator light device 14 and board 11.

To carry out the test, probe 13 is wiped across template 12. Preferably probe 13 is held at an angle no less than 45 degrees and is pressed down to fan out the wire brush but not hard enough to leave openings in the pattern and miss holes in template 12. Overlapped wipes are used to insure full coverage of the entire core. The indicator light comes on under three conditions.

The first condition is for a short between the doughnut and the ground or voltage plane. The short is located by slowly wiping horizontally across the core until the light comes on. The column of holes over which probe 13 comes to a stop is noted. Probe 13 is wiped vertically over that column of holes until the light comes on again. The area where the horizontal and vertical wipes turn on the ligh...