The official IPC spec for minimum thickness is "after" processing.  For current carrying calculations, using the IPC minimum data is probably safest. (Just revised my home-grown calculator a few weeks ago to use IPC minimums.)
18um (0.7mils) is the typical "nominal" value that is used to specify the copper weight (for those that don't like to use ounces).
Thanks Jeffrey... (you were paying attention to Gary's course, were you not?)

[====================================]
Roger M. Stoops, CID
Trimble Navigation Ltd.
[log in to unmask]
[====================================]


-----Original Message-----
From: McGlaughlin, Jeffrey A [mailto:[log in to unmask]]
Sent: Wednesday, October 16, 2002 4:28 PM
To: [log in to unmask]
Subject: [TN] RE: [TN] how thick is ½ ounce copper


Graham -

The official IPC spec is 12.0um internal and 33.0um external  (base foil
with plating).

Jeffrey A. McGlaughlin CID
Sr. Designer
Battelle Memorial Institute
Columbus Ohio
[log in to unmask]



-----Original Message-----
From: Graham Collins [mailto:[log in to unmask]]
Sent: Wednesday, October 16, 2002 3:00 PM
To: [log in to unmask]
Subject: [TN] how thick is ½ ounce copper


Hi Technet!
A simple question for the fab gurus out there - but one over the head of
this assembly grunt.  How thick is ½ ounce copper? 

regards,

Graham Collins
Process Engineer, 
Northrop Grumman Canada Corporation
Halifax
(902) 873-2000 ext 6215

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