In a message dated 05/30/2000 11:41:30 AM Central Daylight Time,
[log in to unmask] writes:

<< David,

 At the risk of creating a debate.... (which I think is always a good
 thing)... I have made PCB's without any protection for the surface of the
 copper clad... and had them last for many years. The issue of having exposed
 copper on a PCB is perhaps overzealously promoted by many designers and QA
 inspectors..  Copper oxidizes when exposed to moisture and air and seals
 it's surface with copper oxide which provides a barrier against further
 oxidation...(snip)

 Clean pristine copper is only necessary to provide good wetability of
 solder...(snip again)

 So, I would suggest, that the copper that you are seeing at the edge of the
 connector is really not a problem. Of course, I welcome other opinions...

  -------------------------------------
 | Bill Brooks, Sr. PCB Designer
 | Zoneworx, Inc.
 | 40925 County Center Drive, STE 200
 | Temecula, CA 92591
 | [log in to unmask]
 | www.zoneworx.com
 | Tel: (909) 296-1226 x 1037 >>

Hi Bill!

You won't get no debate from me. A man that uses logic...I like that! For a
good illustration of what Bill is talking about copper protecting itself with
oxidation all one has to think about is the open wire telegraph system that
wired our country (some lines still survive! If they haven't been stolen for
their copper content), or the Statue of Liberty. The Statue of Liberty was
first built in France in 1884, erected in 1886, stood for 100-years being
exposed to all the elements until it's restoration (begun in 1984). Some more
useless info about the Statue of Liberty:

Visitors climb 354 steps to reach the crown or 192 steps in order to reach
the top of the pedestal. There are 25 windows in the crown which symbolize 25
gemstones found on the earth. The seven rays of the Statue's crown represent
the seven seas and continents of the world. The tablet which the Statue holds
in her left hand reads (in Roman numerals) "July 4th, 1776." The total weight
of copper in the Statue is 62,000 pounds (31 tons) and the total weight of
steel in the Statue is 250,000 pounds (125 tons). Total weight of the
Statue's concrete foundation is 54 million pounds (27,000 tons). The copper
sheeting of the Statue is 3/32 of an inch thick or 2.37mm.

-Steve Gregory-

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