Robert: Fascinating story about ivory PCB's, never heard that one before.

I think there needs to be some clarification on the thickness of 1oz Cu
foil. It may start out at 1.4 mils but it ends up at about 1.3 mils due to
processing steps such as deburring and microetch. So in the real world, the
boards Steve was questioning that were fabricated using 1oz foil should have
a FINISHED Cu foil thickness of 1.3 mils after conventional processing.


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett Wa

425-446-6076



-----Original Message-----
From: Robert Tarzwell [mailto:[log in to unmask]]
Sent: Monday, June 02, 2003 4:37 PM
To: [log in to unmask]
Subject: Re: [TN] Micro-inch to copper weight conversion...


This just goes to show how old I am but when we first started to manufacture
printed circuit boards the only copper you could buy was a very thin sheet
the roofers used to solder flashes around wondows and stuff it was 2 oz
copper and thats how it was sold by the oz. then the lamianted manufatures
started to make laminate I think GE was first, or thats who we got, So even
though theres lots of replies  it all started  with the available copper of
the day. early 1960's
Not realy connected but my grandfather told me about making a sort of
printed board in the 20's by using IVORY and drawing lines between copper
rivets with carbon black in wavy lines to make resistors.
Robert tarzwell
PS some replies have the thickness of 1 oz of copper incorect it is closer
to 1.39 mils. not 1.3

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