Hi, Alejandro,

There is every possibility that wave soldering removed some of the SMT
components. Are you asking about adhesives because you haven't used any so
far, or are you asking because you do use an adhesive but are still losing
components?

The bonding material used to hold components to the board, especially for
side 2 (solder side) when soldering side 1 is intended to have a softening
temperature similar to the soldering temperature to permit rework of the
board in the event of component failure.

If you aren't currently using an adhesive, have a look at the size and/or
weight of the components you're losing. When reflowing the second side of
the board, the only thing holding components to the (under)side already
soldered is the surface tension of the solder. If the components you're
losing are large and/or heavy, a solder wave will very likely sweep them
off.

If you are already using an adhesive, the problem may lie with too high a
pre-heat temperature for wave soldering. Try lowering the temperature and
increasing the soak time.

Regards

Pete Duncan



                    Becerra
                    Alejandro            To:     [log in to unmask]
                    <BecerraA@TCE        cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST
                    .COM>                Group)
                    Sent by:             Subject:     [TN] Adhesive for Bottom Side
                    TechNet
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                    05/08/01
                    08:43 AM
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                    Becerra
                    Alejandro






Hello to All,
I have a question regarding to the adhesive used to hold SMD components
prior to wave soldering.
The problem consists in missing SMD components after wave soldering.
Is it possible that the components fell down during the wave soldering
process because of a high temperature of pre-heaters or solder?


Thanks in advance


Alejandro Becerra
Quality Assurance
(915)841-8439

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