[sdiy] 16pin dip header -- mild warning

[Oren Leavitt]

I've seen that effect, in the tin case below, in old equipment, with 
tube sockets for example.
Electrical contact will be perfectly good - until you bump or move a 
connector or tube.
Then you have to clean the connection to make it good again.
Oxidation has sealed around, but not in between, the two surfaces making 
contact.

Peter Grenader wrote:

>Gold, like titanuim, has a remarkable resiliance to atmopheric contaminants.
>The way I remember it (I used to be a QA who worked a lot with printed
>circuit board production) is that copper, like steel, is considered an
>'active' metal which will completely dissolve over time when subjected to
>normal atmopheric conditions and water serves to accellerate this process.
>
>Tin, like aluminum, reactes somewhat differently in that they are considered
>'passive' metals.  A natural layer of oxidation (usually about 2 mils
>thick)) will coat and actually seal the material underneath from further
>contamination overtime, but it will not go all the way through as it will in
>an active metal.
>
>When properly electroplated, Gold serves and a semi-permanent insulting
>layer which greatly improves a connector's resiliance to corrostion and in
>so doing, regulating the surface resistance and electrical conductivity of
>the substrate underneath..
>
>
>

-- 
Oren Leavitt
oleavitt at ix.netcom.com