Ioan,
Well you answered Bill and I on the wave. So, so much for that. But have
you tried cleaning a bare board and then running it through? You say there
is nothing on the pads. How did you determine that?
Auger definitely requires an outside lab, unless you have a half mil to
spare - dollars, not distance. :) FTIR really requires a chem tech or
chemist, etc.
You can train a good operator to use a wetting balance. They just need a
steady hand and something on the ball. I would say the same for SERA,
although a chemical background for better interpretation would be nice.
$30K - 60K range each to buy.
Bev
-----Original Message-----
From: Tempea, Ioan [mailto:[log in to unmask]]
Sent: April 6, 2001 1:25 PM
To: [log in to unmask]
Subject: Re: [TN] Random absence of solder joints - update
I checked the wave, it's fine. It works well with other boards anyway. I
also passed a couple of bare PCBs and had the same random skips.
Unfortunately there was no chemical or wetting testing involved, it was a
batch of 500, two days job. No time to react, we had to deliver faster than
the time needed to test.
On the other hand, I'm not very familiar with testing either. Which one I
could do in-house, without having qualified personnel?
Thanks again,
Ioan
> -----Original Message-----
> From: Bev Christian [SMTP:[log in to unmask]]
> Sent: Friday, April 06, 2001 12:41 PM
> To: 'TechNet E-Mail Forum.'; 'Tempea, Ioan'
> Subject: RE: [TN] Random absence of solder joints - update
>
> Ioan,
> Are you absolutely sure your wave is stable - no weird up and down
> variations?
> Have you confirmed no organics on the pads prior to soldering via FTIR or
> Auger or simply washing the boards thoroughly before running them?
> Have you used a wetting balance or SERA tester to check the
> solderability/oxide amount on the pads that did not solder?
>
> regards,
> Bev Christian
> Research in Motion
>
> -----Original Message-----
> From: Tempea, Ioan [mailto:[log in to unmask]]
> Sent: April 6, 2001 12:25 PM
> To: [log in to unmask]
> Subject: [TN] Random absence of solder joints - update
>
>
> Hi technos,
>
> and big thanks for the interest in my problem. Now, I tried to follow all
> the leads, I checked the solder mask, I ruled out the contamination, since
> the problem shows on each and every board, checked for oily residues, etc.
>
> To clarify, the problem pads show no sign of having been in contact with
> the
> solder, they are like before waving.
>
> So I still can't put the finger on the cause. However, by hand spraying
> the
> bottoms, or running the foam fluxer at max, we reduced the number of
> problems. We even get, from time to time, fully soldered boards.
>
> Maybe the boards have gone through some thermal cycling that made the
> intermetallics grow, or the pads are oxidized for some reason. Maybe a bad
> batch. I'm sure that a stronger flux would solder very well, but why this
> deviation from the regular process, since we are talking regular boards?
>
> So, the follow up question is:
> what should I do to avoid that the problem reappear while running a future
> job, eventually high volume?
>
> Thanks,
> Ioan
>
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