Steve,
It's a little hard to tell from your description, but one possibility
is outgassing. If you've got moisture in the card, coupled with the
possibility of poor through hole plating, the card may be outgassing
causing blow holes which appear randomly over the card surface. Doing a
bake of the card , with weighing of cards before and after bake, will
verify or eliminate this possibility.
Regards Evan
Evan Jones
Manufacturing/Test Engineer
Bluegum Technology Pty Ltd
PO Box 609, Wangaratta, Australia, 3676
Ph: 61 3 5720 2539 Fax: 61 3 5720 2412
Internet: [log in to unmask]
"Stephen R. Gregory" <[log in to unmask]> on 17/11/98 09:51:17
Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
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To: [log in to unmask]
cc: (bcc: Evan Jones/BGT)
Subject: [TN] Weird Wave Soldering Defect...
Hi Ya'll!
I've been wave soldering some boards today that we've been building
for a
customer over the last 2-months. They're a little 2" X 2" PTH board in a
30-up
panel, and haven't given me a lick of trouble till today...been waving fine
for the past two months. Other than wanting to bow big time while warming
up
before hitting the wave, there really isn't much to em'.
They came out of the wave today with random barrels missing
solder...and
when you look at the barrels that's missing solder, it's like the solder
just
tinned the barrel and lead, and then said "hasta la vista baby, I'm outta
here.." and just dropped outta the holes?!?! It's random too...not
concentrated in any one area. What's got me perplexed is why did it appear
that it wet to the barrel and lead by the way it tinned them, but didn't
stay
up in the barrel? There's no vibration anywhere, and the conveyer runs as
smooth as a babies butt...and I don't use a hot air knife.
Nothing has changed with my settings that I've used over the past
2-months and have been working great up until today. I'm water soluble,
foam
stone fluxer, Soltec Prisma with convection pre-heat, and Kester Flux.
Cleaned
the pot and flux tank this weekend, so I was starting with a nice
dross-less
pot and fresh flux...so what gives? Anybody seen this before? Any ideas?
Thanks in Advance!
-Steve Gregory-
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