Browse Prior Art Database

Lead Frame Measurement Technique

IP.com Disclosure Number: IPCOM000118098D
Original Publication Date: 1996-Sep-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Buettner, HM: AUTHOR [+2]

Abstract

Disclosed is a means of improving parasitic capacitance measurements used to verify electronic assemblies through changes in tester organization and operation.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 59% of the total text.

Lead Frame Measurement Technique

      Disclosed is a means of improving parasitic capacitance
measurements used to verify electronic assemblies through changes in
tester organization and operation.

      This invention allows the extension of an existing measurement
technique used to verify solder joint integrity through capacitance
measurements of card and lead frame by making the measurement into a
relative rather than an absolute measurement through the use of
acquired values and calculations.

      Solder or copper opens are a problem, as in many cases these
connections are untestable but will cause functional problems in
system use.  To address this problem, measurements of parasitic
capacitance formed by the net, lead frame and plate supplied by a
tester are used to determine if a good electrical connection has been
made on the card.  The limitation is that the pins vary in their
capacitance with the type of pin, and with the type and manufacturer
of the leadframe, or lot to lot variations caused by materiels.  This
results in large tolerances that reduce the effectiveness and
stability of the test.

      The solution to the problem of extracting more information from
the measurement is to abandon the use of the technique as an absolute
measurement.  In viewing the measurement for a module input, output
or power pin, the measurement shows itself as ratio governed by
geometries and materiels that do not vary within the module but do
vary from mo...