If the glue dots are properly sized and cured correctly there should be no issues with flux entrapment during the wave soldering process.  It is very common for manufacturers to glue bottom side components and solder the bottom side components in the wave process (no paste necessary).  You will have to be sure the components are such that some solder joints will not be shadowed by the ones in front of it, and the finest pitch doesn't lead to bridging.  Good luck.


----- Message from "Morse, Carrie" <[log in to unmask]> on Mon, 20 Oct 2003 18:15:55 -0400 -----

Subject:

Re: SMT Glue and Paste with Wavesolder

You may also want to try intrusive reflow.

But, to answer your question -- One of the inherent problems with this process is getting glue into the paste and entrapping flux which will cause reliability issues.  

Another solution which may work is simply to mask off those open areas using either a wave pallet, or, if the cost is prohibitive, mask with Kapton (which is also expensive).

-Carrie

-----Original Message-----
From: Richard Lepa [mailto:[log in to unmask]]
Sent: Monday, October 20, 2003 5:35 PM
To: [log in to unmask]
Subject: [TN] SMT Glue and Paste with Wavesolder


Hello Technetters,

We have a very challenging board that has quite a high quantity of SMT parts
on the bottom side, both Rs and Cs and SOICs.  The problem is that I cannot
use the chipwave on the soldering machine because there are large open areas
on the topside of the boards where the solder will flood through.  Since I
can't use the chipwave I get a lot of solder skips in addition to bridging.


The question is:  Has anyone ever used the glue/paste/place/reflow process
and then used the wavesolder to re-solder the bottomside SMT parts and
solder the thru-hole parts?  Are there any inherent problems with using this
process?  Would this process reduce reliability of the parts due to
increased stress levels and intermetallics.  Your help will be greatly
appreciated.

Thanks,

Richard Lepa
Manufacturing Engineer

Brian J. Toleno, Ph.D.
Sr. Applications Chemist
Loctite Electronics
15051 East Don Julian Rd
Industry, CA 91746
Ph: 626-968-6511 x304
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