Stephen R. Gregory wrote:
>
> 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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Steve what you may be seein could be blow holes. PTHs do show random
blow holing where gases escaping out of the plated barrel ( plating
voids) push the solder out. Xsection the barrel with missing solder and
see what you find.

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