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Probe Slide Circuit Card for Step And Repeat Testers

IP.com Disclosure Number: IPCOM000119212D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 5 page(s) / 199K

Publishing Venue

IBM

Related People

Arnold, R: AUTHOR [+3]

Abstract

A probe slide card (PSC) is described which is used in conjunction with a step and repeat tester probe mechanism to provide top surface sensing of circuit board substrates and to provide accurate sensing of varying positions of test probes.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 34% of the total text.

Probe Slide Circuit Card for Step And Repeat Testers

      A probe slide card (PSC) is described which is used in
conjunction with a step and repeat tester probe mechanism to provide
top surface sensing of circuit board substrates and to provide
accurate sensing of varying positions of test probes.

      In prior art, due to the thickness variations of circuit board
substrates, many manual adjustments and readjustments were required
in step and repeat testers before actual measurements could be made.
Step and repeat opens and shorts testers generally require that tool
control computers be advised when it is safe to move the test probes.
The probes are mounted on an X/Y stage and must be raised off the
substrate under test before advancing to the next testing station.
Normally, proximity or photo-electric sensors would be used to signal
the computer of the probe's position.  However, the position of the
probes would change due to the variations in thickness of the
substrate requiring readjustment of the sensors.  The concept
described herein provides a circuit which minimizes adjustment
procedures so that damage to probes can be prevented.

      Fig. 1 is supplied as a reference to show how the probe mount
assembly is positioned above the substrate and how the PSC functions
in conjunction with the components of the assembly.  The probe mount
assembly consists of:  probe interposer 10, which is an adjustable
length spring mechanism; sliding probe 11, which contacts the
substrate; mini-slide 12, attached to probe 11; lift cable 13, which
is attached to mini-slide 12 at one end and air cylinder air spring
14 at the other end; and linear potentiometer 15, which is also
attached to the shaft of air cylinder air spring 14.

      The entire probe mount assembly is cantilevered off an X/Y
stage (not shown).  Sliding probe 11 and interposer 10 are held up by
air spring 14 and lift cable 13 against the underside of press plate
16.  Press plate 16 is moved a fixed distance up and down by means of
a hydraulic motor-driven cam (not shown).  To prevent crushing the
substrate or probe 11, it is necessary to adjust interposer 10 to a
shorter length when a thick substrate is under test. This is required
because press plate 16 has a fixed down and up stroke.  When press
plate 16 is up, probe 11 and slide 12 will be at a higher position
than it was for the thinner substrate.  This is because interposer 10
has been shortened.  Two probe mount assemblies are used with each
step and repeat tester, and each probe assembly utilizes separate
identical circuits.  However, only one circuit is shown.  The circuit
is divided into two identical halves.  One half controls the "A"
probe functions and the other half controls the "B" probe functions.

      Fig. 2 shows the PSC circuitry which controls the probe
functions and is accessed through edge connector J.  The PSC provides
two independent digital input signals to the tool control c...