In reply to the below message.
Make sure that you do not have a tight seal around the Top side of the PWB
with some components especially if they are barrel type electrolytic
capcitors. Seen this happen in the past.

Ivan

Date:    Wed, 31 Oct 2001 22:49:32 -0800
From:    PL <[log in to unmask]>
Subject: Blow holes in solder joints

Hello,

I would like to ask your input on trouble shooting a wave soldering
process that I've encountered producing blow holes on the PCA. The blow
holes were seen at random locations, mostly on small and light caps. The
boards were manufactured in recent weeks. Some board warppage was
noticed after the wave.

Things I tried:
- Boards from a different manufactured date, no effect
- Turned on turbulence wave. It reduced but didn't completely eliminate
the defect
- used stiffener on board edge to reduce board sagging
- used dummy weights on top of parts seen having defect to minimize
"dancing" during wave

How critical is the component lead-to-hole ratio as far as its impact on
solder joint quality?
Could anyone explain how a blow hole can occur and possible steps taken
to eliminate the defect?

Rgds,
Peter