I have switched to SMOBC (solder mask over bare copper) and have noticed that
some of the via's on the board are well covered while others seem to have
only a light coating - I can see the copper hue of the traces - in some via's
there is a slight splash of solder from the plating process. I don't require
plugs for vac. fixtures etc.

My main concern is these boards are subject to harsh conditions (coal mines)
and I'm worried about corrosion at these points.

Has anyone else noticed this with SMOBC?   The board house suggested going to
a smaller drill size for via's (015). Don't suggest a new house - these guys
are great and have been working on it.

What is the IPC spec for min coverage for class 2 boards regarding SMOBC?
 Should I be concerned?

Larry Machak (designer, not cad operator!)
Saminco Inc.

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