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One argument for using is 1/2 oz on internal layers is a reduction in line
width variation. There are very few PWB suppliers that can supply supply a
4 mil line +/-20% on 1oz copper. In addition, mixed copper thicknesses on a
layer pair [i.e. lyr 2 (top)and lyr 3 (bottom)] result in reduced yields. I
also don't believe there is anyone who can honestly quote a 3 mil line
+/-20% on 1oz copper and maintain the specification.
nwbluez
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From: TechNet-request
To: Technet
Subject: Half ounce internals
Date: Friday, February 16, 1996 4:40PM
A strong consideration for not using 1/2 ounce copper on internal
layers, is that you only half the width of copper to make a
connection at the barrel of plating. Possible problems. Be careful.
May not be reliable.
Norm Einarson
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