John/Bill,
we always cover these caps with mold seal prior to waving. The thermocouple
sees a smoother temp cycling and the caps are OK, on the outside at least
and with sampling inspection. The same recommendation came from one
customer, to make up for their poor design.
The question is, is this a real fix, or just an illusion?
Thanks,
Ioan
> -----Original Message-----
> From: John Maxwell [SMTP:[log in to unmask]]
> Sent: Tuesday, June 18, 2002 8:13 PM
> To: [log in to unmask]
> Subject: Re: [TN] Wavesoldering Ceramic Caps
>
> Bill,
> I kind of wish I was still consulting on cracked capacitors as I would
> view
> this as a great business opportunity. Good luck but I do not believe that
> you will ever be successful in wave soldering that case size.
>
> John Maxwell
>
> At 10:30 AM 6/18/02 -0400, you wrote:
> >Hello gang,
> >
> >We have a situation where a board design has some 2225 Ceramic Caps on
> the
> >bottom side of the board. Most of the advisories I've seen indicates that
> >wavesoldering these parts is not recommended. From what I can gather,
> >thermal shock induces micro fractures within the ceramic substrate that
> >leads to component failure. However, I'm thinking that if I could raise
> my
> >normal wave preheat and lower my pot temperature, I could minimize the
> >thermal shock. I could almost have a thermal profile that would be
> similar
> >to reflow soldering. Reflow soldering of these ceramic caps, from what
> I've
> >read, is OK. Some of the articles I've read on this cracking phenomenon
> were
> >written in the late 80's, Is there any newer information out there?
> >
> >Is anyone out there routinely wave soldering these parts that could give
> me
> >some pointers?
> >
> >We use an OA flux with a DI water wash in our process.
> >
> >As always your help is greatly appreciated.
> >
> >Bill Kasprzak
> >Moog Inc. Manufacturing Engineering, Electronics
> >
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