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Coplanarity Inspection Gauge

IP.com Disclosure Number: IPCOM000102416D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 34K

Publishing Venue

IBM

Related People

Beaudin, RE: AUTHOR [+3]

Abstract

A go-no go gauge is used to check whether all flexible elements, e.g., flat leads extending from a computer chip module, are coplanar within a specified limit.

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This is the abbreviated version, containing approximately 100% of the total text.

Coplanarity Inspection Gauge

       A go-no go gauge is used to check whether all flexible
elements, e.g., flat leads extending from a computer chip module, are
coplanar within a specified limit.

      Referring to the figure, a module (not shown) is positioned to
have a base plane of the module parallel to base plate 2 and one or
more of its flat leads 4, 6, 8, 10 in contact with base plate 2,
e.g., lead 4.  Spacers 12 and 14 have dimension D = T + z, where
T is the thickness of a lead and z is the coplanarity tolerance.
Reference flat 16 is movable vertically while maintaining parallelism
of its base with base plate 2.

      In use, reference flat 16 is lowered until it contacts one or
more leads, e.g., lead 8 which indicates a failure to pass the
coplanarity specification or until reference flat 16 contacts spacers
12 and 14 indicating that all leads are coplanar within acceptable
limits.  Detection of contacts may be by any of several means, e.g.,
optical or electrical. A capacitive detector is one that is sensitive
and provides no danger of damaging semiconductor circuits or devices.

      Reference flat 16 may be a rectangular unit having an opening
in its center, thereby allowing a test to determine whether all leads
projecting out of all four sides of a module are within coplanarity
specification or not.