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Electrical Testing by Magnetic Particle Chains

IP.com Disclosure Number: IPCOM000077948D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Romankiw, LT: AUTHOR [+2]

Abstract

In testing ceramic modules, one of the present procedures is to probe each test point with pin probes. Such a procedure suffers from rapid failure due to mechanical wear.

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Electrical Testing by Magnetic Particle Chains

In testing ceramic modules, one of the present procedures is to probe each test point with pin probes. Such a procedure suffers from rapid failure due to mechanical wear.

A master module is proposed which is placed over and in close proximity to a module to be tested, so that they are separated by a small gap. The master module has a separate electrical test point opposite each test point on the module to be tested, and is attached to external wires by embedded conductors.

At the time of testing, a fluid is introduced between the two modules which has a dense suspension of electrically conducting magnetic particles. Upon application of an externally applied magnetic field perpendicular to the module surfaces, the particles form into chains parallel to the magnetic field. The chains are mutually repulsive, so that they space themselves in a uniform way. Thus the fluid becomes electrically conducting along the field direction, but remains an insulator in directions perpendicular to the field. When the density of chains is great enough, each test point on the master module is connected to the corresponding test point on the test module. Thus, there is minimal wear to the master module.

It is noted that the suspension used need not be stable. It can be artificially maintained by ultrasonic or other means until the fluid is in place. It is also noted that the conductors embedded in the master module may be of magnetic mat...