Not exactly like that but I have seen strange corrosion under mask follow
via holes from one side of the board to another. The root cause was a
leaking battery. Something sort of Electrochemical action caused the
corrosion to migrate under the mask and generally not jump from one circuit
to another.

I wonder if the case instance of where it appears to jump from the plane to
the trace isn't in fact two cases one from the via in the plane and one from
the component through hole itself. C-35, was it removed? A failed
electrolytic cap?

What is the nasty brown near J11, component side.

On the solder source side near S21 switch 4, what is that big blob adjacent
to the land?

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Monday, December 04, 2006 11:27 AM
To: [log in to unmask]
Subject: [TN] water water everywhere!

The following files show the two sides of a PCB in a professional weather
station. This shows four dark areas which the manufacturer has ascribed to
water penetration. These are centred on a hole. The whole thing seems funny
to me, as it has happened on only a few of the holes.
I understand that it was housed in a water-tight case, not very far from the
Pacific coast. I was not able to ascertain the laminate type, but it would
not surpise me if it were paper based (FR3?).

Has anyone seen anything like this?

Brian

http://www.realweatherstation.com/FILES/DSCN9441.JPG
http://www.realweatherstation.com/FILES/DSCN9440.JPG

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