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Browse Prior Art Database

Automated Functionality Testing at Signal Core Level

IP.com Disclosure Number: IPCOM000100724D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 81K

Publishing Venue

IBM

Related People

Wyche, MB: AUTHOR

Abstract

This article describes an automated tester that has the capability to check conductors at the signal core level for Characteristic Impedance (Zo = + 10%), shorts, opens, identify narrow/wide line width locations, narrow/wide line thicknesses and narrow/wide dielectric spacing. In effect, this tester can be used as a means to dramatically reduce the amount of visual inspection required by routine manufacturing test procedures by rapidly weeding out defective or out of specification Zo cards/boards. It can also be used as a monitor for the manufacturing process, i.e., deviation in conductor line dimensions.

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Automated Functionality Testing at Signal Core Level

       This article describes an automated tester that has the
capability to check conductors at the signal core level for
Characteristic Impedance (Zo = + 10%), shorts, opens, identify
narrow/wide line width locations, narrow/wide line thicknesses and
narrow/wide dielectric spacing.  In effect, this tester can be used
as a means to dramatically reduce the amount of visual inspection
required by routine manufacturing test procedures by rapidly weeding
out defective or out of specification Zo cards/boards.  It can also
be used as a monitor for the manufacturing process, i.e., deviation
in conductor line dimensions.

      This approach offers a practical method to allow robotic Zo
testing (100%) of printed circuited lines at the signal core level.

      To perform Time Domain Reflectometry (TDR) measurements on
printed circuits at the signal core level with no voltage planes
present, a reference plane is necessary.  The essence of this unique
feature of this idea is to provide pseudo reference planes for the
signal core to be tested.  This action forms a triplate structure
with geometries similar to the laminated composite so that the
electrical characteristics of this structure would be similar to the
finished package.

      The figure shows a signal core sandwiched between a top and
bottom reference plane, forming a triplate transmission line
structure.  The bottom reference plane has copper foil (1 oz.) bonded
to a dense foam dielectric.  The top reference plane must have
clearance holes corresponding to the Platted Through Holes (PTHs) or
the signal core's PTHs can be probed.  Drilled power core i...