Wave soldering - some questions

[siliconmike]

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:
http://www.apsgold.com/pdf_public/Bdipper.pdf

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

Thank you
Mike

 

[Phat Bytestard]

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.

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

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

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.

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?

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.

And are there cheaper semi-automatic wave soldering machines?

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.

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

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.

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

snip

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

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

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?

 

[siliconmike]

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.

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?

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.

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

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?

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.

 

[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?

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..

 

[Phat Bytestard]

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?

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.

 

[Iain Campbell]

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:
http://www.apsgold.com/pdf_public/Bdipper.pdf

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

Thank you
Mike

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