Browse Prior Art Database

Independent Floating Test Module

IP.com Disclosure Number: IPCOM000108496D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Brown, SF: AUTHOR [+4]

Abstract

The drive to miniaturization creates new demands on the Printed Circuit Board (PCB) manufacturing process. The PCB electrical test process must compensate for X-Y variance in the relative location of numerous target contact points on a unit under test, with multiple varying boards of the same design tested on a common test fixture. The key concept of this disclosure are to divide the board design into multiple zones and to design a test fixture with independent modules which align locally to these zones.

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Independent Floating Test Module

       The drive to miniaturization creates new demands on the
Printed Circuit Board (PCB) manufacturing process.  The PCB
electrical test process must compensate for X-Y variance in the
relative location of numerous target contact points on a unit under
test, with multiple varying boards of the same design tested on a
common test fixture.  The key concept of this disclosure are to
divide the board design into multiple zones and to design a test
fixture with independent modules which align locally to these zones.

      Fig. 1 shows a floating module designed to align independently
to a fine pitch feature site - allowing reliable contact at each
designated test point for electrical test.  Multiple independent
modules in one fixture help to overcome accumulated tolerances in the
PCB and in the test fixture, found to be a problem when locating an
entire board on a rigid test fixture with a single set of tooling
pins.

      With each test, the modules of test probes float in the test
fixture independently and align to the fine pitch features,
compensating for growth, shrinkage, misregistration, and rotational
variance affecting location of test sites (copper features) on the
PCB. drilled holes near a fine pitch area mate with the
tooling/alignment pins shown from the side in Fig. 2.  These pins
enter the drilled holes in the PCB and align the module to the test
site before the probes make contact with the fine pitch copper
fea...