Werner,
You are thinking in only the PCB space.  I have in my hot little hands a cardboard tube from EM Science that was filled with “Copper ACS Foil, Electrolytic”.  And as you probably know ASC standards for the American Chemical Society and adding that to the label of your material is pretty serious business.  The assay beside the main title portion of the label says Assay Min 99.9% and then it goes on to list the impurities, all at very low levels. So there does indeed appear to exist electrolytic copper in the purity range I asked about.
Bev
RIM
From: Werner Engelmaier [mailto:[log in to unmask]]
Sent: Wednesday, October 20, 2010 5:58 PM
To: [log in to unmask]; Bev Christian
Subject: Re: [TN] Want to buy electrolytic copper foil

Hi Bev,
Electrolytic copper foil of at least 99.9% purity is essentially a contradiction in terms. Commercial electrolytic Cu foil is plated at very high plating current densities—for reasons of economy, of course, which requires quite a witches brew of organic and other additives to be able to plate Cu with good physical properties and at a high rate. Some of these organics plate out on the grain boundaries, and that is the reason why Cu foil is sold by weight [oz/ft2] and with approximate thickness—the density is a variable.

Werner
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-----Original Message-----
From: Bev Christian <[log in to unmask]>
To: [log in to unmask]
Sent: Wed, Oct 20, 2010 2:26 pm
Subject: [TN] Want to buy electrolytic copper foil

TechNetters,







Where can I buy a roll of 0.002" thick electrolytic copper foil of at least







99.9% purity?







Bev







RIM














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