Mail*Link(r) SMTP               FWD>copper thickness

Gary,

The primary reason for "thick" copper inner layers is to reduce the electrical
resistance of the power/ground plane distribution system.  If you go from 70
micrometer [2oz/sq.ft] to 35 micrometer [1 oz/sq.ft.] thick power/ground plane
system, you'll double the dc (direct current) voltage drops with the power
ground system.  Depending on the frequency(ies) of operation, the effect on
high frequency analog/digital signals may not be as great.

A secondary concern is that some designs use the internal "thick" copper
layers for thermal spreaders to minimize the local increase of temperature.

Be careful about reducing inner power / ground planes without a good analysis
/ understanding of the design requirements.

Ralph Hersey
Lawrence Livermore National Laboratory
e-mail:  [log in to unmask]

--------------------------------------
Date: 4/29/96 6:39 AM
From: [log in to unmask]
Would like input on the subject of 1 oz. vs. 2 oz copper thickness on inner
layers. What types of end products would be affected if 1 oz. were
substituted for 2 oz? What design considerations are most critical? Is it
safe to say that 1 oz. vs. 2 oz. should no longer be an issue? 
Thank you for input.
Gary Longman
Electropac


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