Wave soldering - some questions

We make about 3000 Nos. of 2" x 3" through-hole boards a month. Its not lead free though.

Currently we are using solder pot to solder all boards. We simply flux the board with a sprayer and dip it into the pot using nose pliers. After 3 seconds we lift up the board.

But this seems to be a dirty way since the components are subjected to thermal shock.

But the good part is that we can cut the component leads *after* the soldering. That way we don't have to pre-form certain components that could be prone to popping off the board before handling.

Unfortunately, we are not in a position to invest in an automatic wave soldering machine.

Are there manual machines that could pre-heat the board and dip it into a solder pot?

Or do you suggest that in the first place, a wave solder action is superior to dipping action, as far as the thermal shock prevention is concerned?

And are there cheaper semi-automatic wave soldering machines?

In case of wave soldering, is it necessary to trim leads *before* soldering?

What do you comment of this product - Big dipper - in our context:

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Any kind of advise to economically improve our method would be very much helpful.

Thank you Mike

Reply to
siliconmike
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On 17 Jul 2006 01:29:29 -0700, "siliconmike" Gave us:

For a board that size, at those throughput numbers, I wouldn't either. Threat your process technicians well though. They deserve it.

A good well controlled toaster oven. You also have to be careful after the solder portion of the process as it takes more than a few seconds for the solder to solidify. Also, water soluble fluxes and a good stainless interior magic chef dishwasher or the like is nice. Your town may require you to use some filtration system on your water cleaning system.

As long as you have a short pre-heat cycle that offsets the solder pot temp well enough, you won't overtly shock the parts.

To get into a proper wave solder setup is expensive to say the least. This is why many product makers have resorted to contract manufacturing over the last few decades. It is a far cheaper solution for some product makers.

You should even have them trimmed fairly well for solder pot methodology. For wave soldering, the ideal length is that which requires no further handling after the solder process.

snip

It looks bigger than what you need, and lacks some controls seemingly. I see no preheat station there either.

There are good "baking ovens" out there that have very good thermal controls. You could find one, and preheat your boards.

The big question would really be: are you having some failures that are leading you to believe that lack of preheating the assembly is the root cause?

Reply to
Phat Bytestard

We have presets and certain caps on board, that are not water friendly. Thats why we use no-clean flux and then use ultrasonic pot filled with IPA to clean the boards. But why do you suggest water soluble flux?

Most leads are trimmed during component pre-forming. But there are few of them that are trimmed after soldering. But why do you suggest that lead trimming is important before soldering?

For wave soldering, the ideal length is that which

Yes. There are certain failures that baffle us. And we want to make sure that they are not due to component degradation at the time of soldering.

Reply to
siliconmike

On 17 Jul 2006 02:53:37 -0700, "siliconmike" Gave us:

You solution and IPA is fine, but you have to watch exposure times on vented EL caps with that as well.

As far as water friendliness, you should bake your boards at 60C for a half hour of more after cleaning with water anyway. Transformers and even EL caps (usually) are second operation, hand solder jobs... even with no clean.

IPA works. And IPA based fluxes or rosin core even, cleaned properly. Heated IPA is better than mere ultrasonics as well. Careful though as it is flammable, which I am sure you knew..

Reply to
Phat Bytestard

On 17 Jul 2006 02:53:37 -0700, "siliconmike" Gave us:

The ideal solder joint is one that does not require any operations after it is formed. Lead trimming can and usually does apply tensile stresses to the lead, and that pulls on the microstructure of the solder joint. This is why only "single lead at a time clipping" is "legal". The real problem is that a clipped lead exposes an area of the solder joint where multiple metals are exposed to oxygen, and a galvanic corrosive action can occur in certain atmospheric settings. An unclipped joint has only tin lead solder exposed.

Reply to
Phat Bytestard

You could try "Pin in Hole Reflow". Basically, you paste the board as though it was surface mount (simplistic to say, a little more difficult to do), fit the components then put it through a reflow oven. Far cleaner and easier to manage than wave solder. Given that you can paste it manually or with a machine, and place the components manually, the oven is your only real capital expense. And you can get one a lot cheaper than a wave solder set up.

By the sound of it, though, you might do better looking at sub-contracting the manufacturing out.

Good luck,

Schneckster

Reply to
Iain Campbell

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