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Subject: Re: [TN] Copper plating & Copper thickness
Date: Wed, 11 Nov 1998 11:11:53 EST
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Les - Thanks for your excellent piece explaining in greater detail the factors
affecting surface and hole copper plating.  The boundary layer is also
referred to in some circles as the diffusion layer.

It should also be noted that impingement platers were a great idea but fell
far short of expectations.  The initial application of that technology was to
gain higher current densities.  We all know what's happened to hole sizes and
board thicknesses over the years.

Enter airless acid copper plating.  Solution transfer through the holes is
significantly enhanced if this kind of agitation is properly set up and
employed.  Thus, surface to hole plating thickness disparity is minimized.
I'm currently working on technology that will go even further to promoting
uniform copper distribution over the entire surface of the board, including in
the holes.  Why settle for getting a 1.0 mil minimum of copper in the hole and
1.5  or even 2.0 mils everywhere else, especially around the perimeter of the
board?  And at low durrent densities.  Why not dispense with the border (and
other thieving designs) and still achieve this?  If you're interested, we
should talk off line about it.

Regards, Roger Mouton