We had a similar situation with our first two-sided board, which also wasn't layed
out particularly well for waving, especially without a chip wave....SOT23's, 0603's, big tantalums, inductors, etc. Our motivation was avoiding the investment in a chip wave just for the one two-sided assembly that we were going to produce at the time.

It didn't work well, right out of the chute.  The solder fillets all showed signs of disturbance, some minor, some really ugly.  We surmised it was a function of contraction of the epoxy concurrently with the solder going solid.  We just opted to get a good turbulent chip wave to resolve the shadowing instead.  It could be that a thorough evaluation of adhesives might point you in the right direction, but that's not the direction we went.


-----Original Message-----
From: Paul Truit [mailto:[log in to unmask]]
Sent: Friday, November 15, 2002 7:37 AM
To: [log in to unmask]
Subject: [TN] Glue dispensing


In our manufacturing life when doing double sided SMT assy's that
included through hole We have been using the stencil printer to apply
the adhesive for the SMT components.

I have a project that requires this method but the board just isn't
designed for a high yield process through the wave solder machine due to
component shadowing.  Has anyone used a solder paste approach then put
the boards through an adhesive dispenser?  Thus you already have good
solder joints on the SMT parts ... glue to hold them down ... and when
the wave solder machine solders the TH parts the SMT parts are still
soldered.

Any thoughts of this process for increasing the yield of these boards?
Redesign is pretty much out of the question.

Are the bench top machines i.e. the Camelot 1414 a good match for this
type of application?  Or is there a different economical (Got to use
that word now days) solution.  We're running 3000 piece lot sizes with
approximately 40+ SMT components.

--
Paul Truit, Mfg. Eng.
RBB Systems, Inc.
4265C E. Lincolnway
Wooster, OH  44691
Ph. (330) 567-2906 ext 514
Fax (330) 263-5324
Email: [log in to unmask]

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