Steve,

It looks more like an extreme case of air-bubbles in the
copper plating tank, trapped by the plating resist. The pits have the
typical feature of all having the same orientation, along the lower track
edges
 This edge would during plating have been the upper.

pits.jpg contains one 45 deg track segment. You will note the
absense of pits there, as the bubbles could move "upwards"
on that segment.
There are probably also pits underneath the HASL coating.
Sure, this is not good workmanship.

The good part is that you will most likely still have the full
base copper thickness at the "bottom of the pits", as it
would have been protected by the metallic etch resist,
plated on top of the electro-deposited copper,

A microsection could easily reveal this. Or you could try to
scrape away the soldermask in the pits with a knife-tip.

regards

Torben Oesteraa
Printca AS.

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