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September 2000

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Subject:
From:
Miguel Vallejo <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 25 Sep 2000 17:13:05 -0700
Content-Type:
text/plain
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text/plain (94 lines)
If I understand correctly, you are re-flowing the solder joint a second time
(when it goes through the wave solder). Doesn't that raise a concern
regarding increased intermetalic layer?

> ----------
> From:         Jason Gregory[SMTP:[log in to unmask]]
> Sent:         Sunday, September 24, 2000 6:45 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Bottom Side wave soldering of SMT parts
>
> Mike,
> We print paste and dispense adhesive as a rule. It adds quite a bit of
> insurance to the underside of our boards. We have experimented with no
> pasting, just wave-soldering. Our yields went down at ICT and open
> capacitors went through the roof. We run no-clean for the record. Hope
> this
> helps.
>
> Jason Gregory
> Manufacturing Supervisor
> ACT Manufacturing
> Corinth, MS. 38834
> (662)287-3771 x470
> [log in to unmask]
>
> > -----Original Message-----
> > From: Mike Sewell [SMTP:[log in to unmask]]
> > Sent: Friday, September 22, 2000 3:39 PM
> > To:   [log in to unmask]
> > Subject:      [TN] Bottom Side wave soldering of SMT parts
> >
> > We build a mixed technology board here with bottom side SMT (SOTs, small
> > chips, all laid out not to solder, ie..90 out from each other) and get
> > very
> > poor yield from wave  (chip + lamda) solder.  We print the adhesive on,
> > P&P,
> > cure, stuff, wave then TOUCH UP.  My question is: what about printing
> > paste,
> > dispensing glue (or vice versa), P&P, reflow/cure, stuff, then wave?
> Will
> > having an existing joint make life easier on wave skips, or will the
> wave
> > disturb the skipped joints to the point of needing touch up?
> >
> > Haven't tried it yet because our dispenser is down,
> > Mike Sewell
> >
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