Hello T'Netters,
Recently our lab provided qualification testing of a board house for an OEM.
The OEM requires surface copper of a particular thickness (e.g., 2.8 - 3.6
mil).
We provided measurements from a number of cross-sections.
We measured both PTH copper dimensions and, elsewhere on the board,
provided typical surface copper measurements.  The stack-up measurments
of the PTH's evidenced slightly less than the minimum surface copper
thickness
mandated by the OEM.  So, the OEM rejected the board house.
Is it fair to use surface copper measurements near PTH's to characterize the
copper thickness of PWB's?  Could subsequent processing in the absence
of solder resist result in lowered copper thickness?  Does any military or
industry specification mandate or even suggest appropriate areas for surface
copper measurement?
TIA for any insights offered.

Mike Simms
Chemist
Trace Laboratories - Central
1150 West Euclid Avenue
Palatine, IL  60067

phone  847-934-5300
fax      847-934-4600
www.tracelabs.com

Notice:  This message is confidential and intended for the private use of
the addressee only.

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