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May 1998

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Subject:
Re: HASL alternative.Exposed copper
From:
Lenny Kurup <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 26 May 1998 14:55:34 -0400
Content-Type:
TEXT/PLAIN
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TEXT/PLAIN (60 lines) 
Hi All,

The issue of exposed copper, and subsequent oxidation, for an electronic
application, is very important, not only from a joint defect point of view
but, also from a trace conductor viewpoint. A typical trace and/or pad is
built with a design for a minimum conduction amount, both heat and
electrical characteristics are calculated based on a thickness of
copper. Alter the copper thickness and/or purity, by oxidation for
instance, and you alter the characteristics of the circuit, which may lead
to subsequent field failures.

LK

On Tue, 26 May 1998, SteveZeva wrote:

> Hi Nicolas!
>
>      As far as the exposed copper that results from an OSP process, there
> isn't an issue as far as I know. Yes the copper will oxidize, but from the
> little bit I know about metallurgy, it's my understanding is that the copper
> will be coated with a layer of oxidation, and then it slows down dramatically.
> For a illustration of that just think about some of the copper water lines in
> old houses, the copper telephone lines exposed to the elements for years and
> years...that shows that it takes quite a while for copper to deteriorate.
>
>      Somebody correct me if I'm wrong about this, but the exposed copper
> problems that are defects usually have something to do with the exposed copper
> being an indicator of some other problem, not the fact that the copper itself
> is exposed. Oxidation of the copper is normally only a problem when trying to
> solder to it...
>
> C-ya,
>
> -Steve Gregory-
>
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