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| From [log in to unmask] Thu Feb 8 12: |
33:29 1996 |
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Take an average panel with say 9000 holes and assume there are 6000 non
functional pads. If it is a 4 layer with 1oz inner layers then you have nearly 3
mil of copper extra for each hole with NFP's. This amounts to 18 inches of extra
copper drilled during that drills life. Multiply that up for 6,8, and 10 layers,
and then 2oz and even 3oz inners. Ground planes are the biggest culprit, as
tracked layers generally have thinner 0.5oz copper which is not so bad.
There may be other reasons we manufacturers have for keeping them to overcome
processing problems on particular designs, but we are talking about the majority
of MLB's and not the exceptional cases. Let's keep them in during the design
stage but let the manufacturer remove them or keep them depending on their
judgement for particular designs or process.
Designers cannot object to them being left in and we do not want to persudae
them that they should not be removed.
--
Paul Gould
[log in to unmask]
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