use IPC 2221, and use the coupons. This will allow you to follow the build
up of layers through plating and drilling. Any destructive testing can be
done on these avoiding having to destroy a sample of the production board.

Regards,

Ted

-----Original Message-----
From: Brian Guralnick [mailto:[EMAIL PROTECTED]]
Sent: Monday, December 16, 2002 1:07 PM
To: Protel EDA Forum
Subject: [PEDA] PCB Layout Tricks to help identify Lemmon PCB's.


Hi Everyone,

    Last year, I had a run of 1000 PCB's (4 layer) where 80% initially
passed QC, then 90% of the pass PCBs failed after a few days
of use.  After exhaustive investigation, I cut right through the PCB with a
huge pair of scissors.  It turned out the PCB's middle
layers had around 25% the normal copper thickness & all the traces where
also around -4 mil in some areas.

    Are there any tricks, test patterns where I could easily determine the
following for a 16 layer PCB panel without having to
slice up the panel:

1) Alignment of each of the middle layers.
2) Vertical thickness of the copper on the middle layers.
3) Horizontal thickness of the traces on the middle layers.
4) Drill hole alignment for all of the layers.


Thanks,
Merry Christmas, Happy New Year.
____________
Brian Guralnick
[EMAIL PROTECTED]
(514) 624-4003

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