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Date: | Mon, 21 Aug 95 5:13:45 MDT |
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DOES THE NEW REVISION OF IPC-A-600 PENDING RELEASE BY SEPTEMBER ACCEPT
EXPOSE COPPER AND TO WHAT EXTEND ?
AUGUSTINE 8/21
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From : [log in to unmask] (R_R_HOLMES)
Date : Sunday, March 5, 1995 04:31:39 HKT
AT&T allows exposed Cu on PWB's, and do not consider it a reliability
threat.
This issue has been a topic of some discussion with Bellcore who controls
specifications for domestic tele-communications equipment. They now
accept
the fact that exposed Cu is not a reliability threat. One of the best
papers
on the subject was written by two Bellcore scientists:
"THE SURFACE COMPOSITION OF COPPER WITH INDOOR EXPOSURES RANGING FROM 3 TO
49
YEARS ; Rudolf Schubert and Susan M. D'Egidio; Corrosion Science, Vol
30
No 10 pp999-1008, 1990
Thia paper discusses the use of Ager spectrocopy to investigate surface
films
on copper bus bars that had been installed as early as 1939. They found
films
of 10 to 100 nanometers. These films differ chemically and in thickness
from
fils formed in accelerated atmosphere corrosion chambers.
I hope this reference is of use.
R. R. Holmes
AT&T
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Did anyone have any idea where I could find any article or reference about
the copper expose on the PCB (GOOD OR BAD) ?
thanks
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