Browse Prior Art Database

Four Point Probe for Peripheral Brazed Pins

IP.com Disclosure Number: IPCOM000051955D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Goldmann, LS: AUTHOR

Abstract

In-situ electrical testing of pin substrate joints is currently very difficult. Broken pins occurring during card assembly and final card processing are a significant multilayer ceramic (MLC) problem. It is often difficult to electrically isolate and verify the loose pin unless the module is removed from the card. In the vast majority of these cases, the broken pin is on a corner or outer row.

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Four Point Probe for Peripheral Brazed Pins

In-situ electrical testing of pin substrate joints is currently very difficult. Broken pins occurring during card assembly and final card processing are a significant multilayer ceramic (MLC) problem. It is often difficult to electrically isolate and verify the loose pin unless the module is removed from the card. In the vast majority of these cases, the broken pin is on a corner or outer row.

The technique proposed here is a probe with plastic housing and metal contacts which snaps on the side of the substrate, making contact to the pins, and separately to the module pad outside the pin area. The spacing between the pin and the outer contacts is defined by the dimensions of the plastic housing, and is chosen to be beyond the point in the brazed fillet where cracks are observed. This arrangement allows a four-point measurement to be made of the bottom of the pin and braze joint. The probe is shown in Figs. 1 and 2.

It may be noted that even if the pin is far off center on a module pad, one pad spring will be in contact with the pad and a three-point measurement will be possible.

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