Lee is the man, living now in retirement (my ass) and it works.

Earl Moon
----- Original Message -----
From: Mcmaster, Michael <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 14, 1999 10:19 AM
Subject: Re: [TN] Measuring copper thickness @ incoming inspection


> For OL, you can use an eddy current tester or something similar.  We use
> a couple of different tools from CMI.  You can reach them at
> http://www.cmiinternational.com/
>
> For IL, you could put a resistance coupon on the board.
>
> Lee Ritchey includes a nifty little trick in his High-Speed PCB and
> System Design Course.  He calls it a stacking stripe.  I'll assume he
> won't mind my posting it here in exchange for a plug to take his course
> (last I looked it was offered through the Continuing Education in
> Engineering, University Extension at University of California, Berkeley
> - Go Bears!)  He places a strip of copper 50 mils wide by 200 mils long
> on layer 1.  On each successive layer, the strip is 25 mils longer.  The
> strip is placed so that the centerline of the 50 mil width will be on
> the finished card edge.  When the board is routed, the strips are
> exposed and can be inspected without microsection.  It looks something
> like this for a 4-layer board.
>
> Layer 1  _______
> Layer 2  __________
> Layer 3  _____________
> Layer 4  ________________
>
>
> The correct order of layers and copper weights can be verified this way.
> He even includes a trace of a specific width so that proper etching can
> be verified.  Please note that this is contrary to the typical
> requirement to avoid exposing copper on the card edge.  If you use this,
> you'll probably need to specify that exposed copper is acceptable in the
> stacking stripe area of the card.   Obviously the stacking stripe needs
> to be isolated from functional circuits and planes inside the card.
>
>         ----------
>         From:  Brian Gaynor [SMTP:[log in to unmask]]
>         Sent:  Tuesday, September 14, 1999 12:53 AM
>         To:  [log in to unmask]
>         Subject:  [TN] Measuring copper thickness @ incoming inspection
>
>         Hi,
>         What devices or techniques do you know of that can measure the
> thickness
>         of external & internal copper on a PWB from a PWB Manufacturer
> that does not
>         involve micro-section?
>
>         Best regards,
>         Brian Gaynor
>         Artesyn Technologies Europe.
>         [log in to unmask]
>
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