I had some solder paste that was sent to my employer as a sample. The
boss gave each one of us a tube, which was 10 CC of paste in a
syringe. On DIP and through hole components, it worked great. But, it
was worthless (other stronger words inserted here) beyond belief for
SMT.

We use pyropens for rework, which is butane powered hot air. Except it
has a twist, the hot air is passed through a catalyst, which consumes
the oxygen. The lack of oxygen in the output of the hot air stream
makes the solder job clean and wetting is very fast and easy because
the part and the solder doesn't oxidize when the heat is applied. The
lack of oxygen removes the need to preheat and lets the flux do it's
job-there is really no need to preheat if you can get rid of the
oxygen in the hot air stream, try it, you'll like it!

If someone would make an inexpensive dispenser for distributing the
paste evenly, I think the paste would be viable for soldering and for
rework. Without a means to dispense small quantities of paste on
demand, the paste method is truly useless (IMHO).

In the end, we used the paste for soldering wires to some thermal
switches we were building, a horrible waste of some perfectly good
product! But, the company that made the paste wanted $450 for a fancy
air dispenser, that should have cost $69. Our opinion was that the
boss should save the money and we told him so. Since that time, we had
2 visits from sales people who tried to sell us paste. In each case,
the paste was reasonably priced, but the applicator was worthless or
cost 5 times what it should have!

We are doing alot more rework with SMT these days, so are still
looking for a solder paste with a reasonably priced dispenser.

Does anyone know of a proper dispenser for solder paste, such as an
air driven or a fine pitched thread to mechanically drive the syringe
in small increments? Or, perhaps a small linear stepping motor can be
used?

Regards

T

e-male me durectly

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