Hi LK ,
I think You are dealing with microelectronics and not with PCB . On " normal
" PCB there are some variations in tracks thickness ( due to plating
processes ) and widthness ( due to etching process ) in terms of several
microns .
Corrosion on exposed copper at edges of soldered pads is completly neglible
compared to mentioned above .
At 14:55 26/05/98 -0400, you wrote:
>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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