Hi Annie -

I've got to agree with everything Earl has said, but let me add a few thoughts
-

If you have barrel wall voids, of any type, including glass protrusions, then
you have a situation where process moistures may enter prior to hitting the
solder pot.  You may also have some residual stuff in barrel wall voids from
the board fab processes.  Lastly, I have had cases where the resin in the
laminates will outgas slightly when we hit the solder pot.

IMHO the only differences between blowholes and pinholes are the timing of the
occurence and the volume of gas dispelled from the source.  It might be worth
while to DPA an assembled board to determine if the microsections will help
pinpoint the physical origins.

One non-destructive approach - shine a fairly intense light into the laminate
structure adjacent to a barrel while viewing the interior barrel wall from a
45 degree angle.  If you have a void (and if the light is angled just right)
you can pick up a pin-prick of light thru the barrel wall.

Other possibilities: organics on the board surface - havent seen this one in
many years; flux volatiles - generally solved by a bit longer preheat cycle.

Good luck - Kelly

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