Luckily it was not a weak-kneed audience.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of R Sedlak
Sent: Thursday, March 08, 2012 12:14 AM
To: [log in to unmask]
Subject: [TN] Excessive Copper Plating
A LONG LONG time ago, Hewlett Packard made their own circuit boards... in today’s world this borders on the unimaginable.... and even more unimaginable for so long ago, they foresaw the problem of uniform Copper plating in small high aspect ratio holes.
So, they did the H-P thing, they threw lots of money at the trying to solve the problem. They hired a PhD Electrochemist, gave him a whole department, and he performed experiments which were unimaginably expensive and difficult.
Imagine making a multilayer circuit board using Nickel, instead of Copper, as the innerlayer foil, and then instead of making the hole conductive using electroless Copper, connect each layer separately to the rectifier, and thus plating only the Nickel foils with Copper. Then sectioning the board, and measuring the amount of Copper plated on each layer! Phew!
When they folded their tents, and gave up making their own boards, they closed this department. The head of the department was not allowed to publish his work,
but was allowed to present it at a talk to the local Electrochemical Society meeting. I was at this presentation.
His conclusion was that mass transport of Copper ions had essentially zero to do with the uniformity of plating down the hole. He did not solve the problem, but he did arrive at profound conclusions, key among them was that the solution to the problem of uniform plating would come from the chemistry of the bath, not the apparatus for plating....
Offered for your information..
Rudy Sedlak
RD Chemical Company
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