Browse Prior Art Database

Four Point Probe Fixture

IP.com Disclosure Number: IPCOM000049303D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Andreasen, AC: AUTHOR [+2]

Abstract

This hand-held fixture allows non-destructive four-point probing of fragile additively-plated copper circuit lines on printed circuit cards and boards. Contacting the line is simplified since the fixture uses a matrix probe that allows four-point contacting to be accomplished with a two-point geometry. In using a matrix probe, the total contact surface area is increased, thereby significantly reducing the average stress under the probe and the resultant stress gradient in the surrounding copper line for a given force as compared to a standard instrumentation probe.

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Four Point Probe Fixture

This hand-held fixture allows non-destructive four-point probing of fragile additively-plated copper circuit lines on printed circuit cards and boards. Contacting the line is simplified since the fixture uses a matrix probe that allows four-point contacting to be accomplished with a two-point geometry. In using a matrix probe, the total contact surface area is increased, thereby significantly reducing the average stress under the probe and the resultant stress gradient in the surrounding copper line for a given force as compared to a standard instrumentation probe.

In the construction of the matrix probe body, eight multiwire conductors are bundled as shown in Fig. 1. The bundle is then set in grooves cut into a retaining fixture (not shown) where epoxy is applied to a portion of the bundle. After the epoxy is cured, the bundle is removed from the retaining fixture. This bundle will form the matrix probe, and two such bundles are required.

Referring to Fig. 2, the probe fixture is fabricated from PLEXI-GLAS* stock and epoxy. A probe arm is epoxied to a support body. The probe bundles are set into guide grooves that were previously machined into the probe tip end of the arm and epoxied in place. The probe ends of the bundles are polished flat and rubbed in gold foil. The gold covering prevents oxidation of the otherwise exposed copper conductors.

In interfacing the probe fixture with suitable instrumentation, insulation on the conductors o...