Hi Kevin,
The reflowed tin-lead plate process used by the military (Mil-P-55110)
allowed exposed copper on the vertical edges of the traces.  However, the
boards of any complexity are also conformal coated.  If you are conformal
coating, you are probably OK.  At least you can put together a good story.


No conformal coat?..... look inside you PC one last time

George Franck




>Good Morning,
>
>We usually require soldermask over bare copper and tented vias (less than
>.020").  This typically means that the soldermask is dry film.  If a tented
>via is not required and liquid soldermask is used, it appears that the
>soldermask is suspect to flake off near the via knee, leaving a small amount
>of exposed copper.
>
>Is liquid solder mask over bare copper compliant with vias when the plating
>is eletroless nickel - immersion gold?
>
>Does the plating type matter?
>
>Is the suspect of exposed copper a non-issue?
>
>Thank you in advance of any comments.
>
>Kevin Thorson
>Lockhead Martin
>Eagan, Mn
>
>




>