I have done this many times with success, but on a limited basis (a
     few large parts that would not stay put). Also, we have a large SMD
     connector that sees an extreme mount of vibration. We place all of the
     parts and then the connector, then epoxy copious amounts of Loctite
     3609(by hand, ouch) onto each end of this connector. Adds some nice
     orange color to the board! Then we reflow/cure this together. We
     vibration test the holy crap out of this assembly (36 million cycles
     served). The moral is, try it and see if it works in your process!
     Jeff Hempton
     UT Electronic Controls


______________________________ Forward Header __________________________________
Subject: Re: [TN] Cure and Reflow
Author:  Jorge Engenharia <[log in to unmask]> at Internet
Date:    02/15/2000 10:58 AM


  Murugan;

  I did this in the past to avoid 0603 tombstoning during reflow until new
land size was modified in the board. It worked well !!!
  First we applied solder paste using screen printer and then we applied
glue using a syringe dispense equipment ( Panasonic ) using a double dot
pattern nozzle, this process requires continuos monitoring due some times
you get the nozzle dirt with solder paste. We did this in 1994 when a new
board design was made using 0603 and nobody realize that tombstone could
happen, that time 0603 were a new component for us and until we get the
problem fixed by changing land pattern design and solder paste ( we did a
small DOE study ), we had to apply adhesive to avoid tombstone and keep
production running ( 10000 boards per day !!! )
  The adhesive used were Loctite 3605 ( I am not sure about the number, but
it were red and came in 20 ml syringe package ) and the reflow profile were
the same that I used for solder paste.
  I believe this process is used also for double sided reflow with heavy
components on both sides.

Thanks
Jorge Dourado de Santana
Maintenance / Process Engr
Microtec - Brazil


> -----Original Message-----
> From: Murugan Vasudevan [SMTP:[log in to unmask]]
> Sent: 15 de Fevereiro de 2000 12:24
> To:   [log in to unmask]
> Subject:      [TN] Cure and Reflow
>
> Hi Technetters,
>
> Just wondering if anyone of you have done simultaneous
> cure of SMD adhesives and reflow of solder paste in
> the same pass. Any information/leads on any previous
> experiences with this process will be very helpful.
>
> Thanks,
>
> Murugan.
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