David,
I didn't go into too much detail because I didn't think the communication
warranted it, but your admonition suggests I should.
Firstly, we are a small integrated company with a Process Department of one.
My facilities for this type of experiment are a bench (hard won through a
bit of chicanery on my part), a Pyrex beaker (which I supplied myself) and
access to hot water from the canteen.
The actual conditions of soaking included total immersion in hot water,
replenished on a daily basis, with added wetting agent. (Oh all right,
washing up liquid) and also inverting a board with a BGA already soldered in
place over hot water, replenished daily.
I have also tried reflowing BGAs that have laid around the workshop for over
a year with no moisture protection.
And still I cannot deliberately pop corn the blighters.
Regards
Eric
> -----Original Message-----
> From: David Douthit [SMTP:[log in to unmask]]
> Sent: Monday, November 18, 2002 7:31 PM
> To: TechNet E-Mail Forum.; Eric Dawson
> Subject: Re: [TN] Popcorning
>
> Eric,
>
> Congratulations! You have proved, once again, that water vapor is much
> more permeable than liquid water.
>
> Try "soaking" them in a high humidity condition (>90%) at 40 degrees C
> for 48 hours then running reflow.
>
> David A. Douthit
> Manager
> LoCan LLC
>
> Eric Dawson wrote:
>
> > Werner,
> > I could use some myself for internal quality training.
> > I have recently soaked some BGAs and some quad packs in water for over a
> > week before putting them through a reflow profile. I have yet to produce
> > visible evidence of pop corning.
> > The annoying thing is, a while ago we used some BGAs on a tape where the
> > moisture indicator went just a little pink and they pop corned. The
> visual
> > evidence was fat solder deposits and shorts in the middle of the package
> > where it bowed downwards. My street cred. with the managers around here
> has
> > taken a beating since I have failed to reproduce the problem.
> > Oh well, I'd rather be happy than right.
> > Regards
> > Eric Dawson
> >
> > > -----Original Message-----
> > > From: Werner Engelmaier [SMTP:[log in to unmask]]
> > > Sent: Monday, November 18, 2002 4:02 PM
> > > To: [log in to unmask]
> > > Subject: [TN] Popcorning
> > >
> > > Hi 'Netters,
> > > Could any of share some good pictures of a 'popcorned' component and a
> > > component with delaminated die. I would of course give full credit as
> to
> > > source.
> > >
> > > Thanks,
> > > Werner Engelmaier
> > >
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