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Measurement of Electrical Continuity in Circuit Boards

IP.com Disclosure Number: IPCOM000050923D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Von Gutfeld, RJ: AUTHOR

Abstract

A technology is described for accessing small circuit pads without mechanical contact. The technique permits electrical continuity measurements to be made.

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Measurement of Electrical Continuity in Circuit Boards

A technology is described for accessing small circuit pads without mechanical contact. The technique permits electrical continuity measurements to be made.

Generally, circuit boards require tests to assure electrical continuity of the deposited circuit pattern. For many circuits, it becomes difficult, if not impossible, to access very small circuit pads without the use of special fixtures. It would be highly advantageous to have a way to test circuits for repair purpose without the use of mechanical probes. Generally, mechanical probes are too large or cause damage to the pads.

A quasi contactless method that permits access to small lines and pads for the purpose of circuit (continuity) testing is proposed.

An example is shown in the drawing. Here, it is assumed that connection can readily be made to a ground plane and that electrical continuity is required between a small pad on the board and the ground plane. A focused laser is used to illuminate a small conical region of a photo-conducting fluid over the board: This fluid can be spread out over the entire board, or it may be in the form of a droplet, a gel or a viscous fluid. A small probe is placed in the upper region of the conically illuminated fluid. Photoconduction of the fluid is established by a photochemical reaction, as described by
A. Aviram, Macromolecules 11, 1275 (1978). The relatively slow change in resistivity reported will be greatly increa...