Peter, the problem could actually be with the components, rather than the
boards.
I had a problem with blow holes resulting from additives used by the
component manufacturers to ensure the leads appeared bright and shiny.
A quick way to see if this is the problem is to reflow the coating on leads
with a soldering iron under a microscope. If it bubbles like Alka-Selzer in
a glass of water, the components may be the source of your blow holes.
Good luck,
Terri
> ----------
> From: Busko, Wolfgang[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.
> Sent: Thursday, November 01, 2001 11:00 AM
> To: [log in to unmask]
> Subject: [TN] AW: [TN] Blow holes in solder joints
>
> Peter,
>
> an easy, fast check for outgassing would be using some oil that can
> withstand the temperature and has of course no water-content, apply it to
> a
> through hole and heat the barrel with a solder iron. Best done under a
> microscope for better visibility. You should not see any bubbles from
> outgassing.
> Haven´t done it myself but still remember that advice given here or on
> SMTnet a while ago and connect it somehow with Earl, The Moonman, but
> don´t
> nail me for that one.
>
> I´m not sure if baking those boards will bring any relief.
>
> Good luck
>
> Wolfgang
>
> -----Ursprüngliche Nachricht-----
> Von: PL [mailto:[log in to unmask]]
> Gesendet am: Donnerstag, 1. November 2001 07:50
> An: [log in to unmask]
> Betreff: [TN] 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
>
>
>
> _________________________________________________________
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