Practical DIY or modest cost Vapor Phase - does it exist yet?

[rx8pilot]

I have perused the bowels of the internet and found a small handful of vapor phase DIY experiments. None of them seem practical, effective, or well thought out so far.

After looking at some of the entry-level and above commercial models, I have started to appreciate the challenge to some extent. The cost of the commercial units, even the entry-level, is rather steep. I would not, however, mind spending $1k on parts and building a small system to replace my current convection batch oven. Most of my work is mixed power and signals which is really challenging to reflow.

Any good DIY projects or functional entry-level options? My boards are all small - roughly the size of my hand or so.

Perhaps this is wishful thinking.

[tautech]

Some threads I remember:

https://www.eevblog.com/forum/projects/vapour-phase-soldering/
https://www.eevblog.com/forum/reviews/mini-blog-imdes-vapour-phase-purchase/

[Kjelt]

Most expensive part is the active cooler to keep the upper area cool.
You could use watercooling and shop for a chinese watercooler for lasers to get there.
Still stainless steel holder, elevator plateau, closing lid, watercooler, steppers and drivers, PSU, DIY electronic control, $1k DIY would be feasible but will cost you much more in time.

[spongle]

I've been thinking about getting into it myself the last couple weeks. I plan to start with a very basic system, no platform motion or PID heating, fancy recovery/condensation systems etc. I hope it can still be an improvement over my current butchered toaster oven. The main concerns I see are not exceeding the decomposition temperature (~280C) at the heating surface, and of course not creating an explosion with a sealed vessel.

I have found a source that supplies small quantities of Galden HT-230 at a reasonable price, although I've not confirmed yet they will sell to individuals: http://www.synquestlabs.com/product/id/52503.html

If it goes well I would be interested in collaborating on a more sophisticated system that could be produced as a kit/open hardware product at some point.

[SMTech]

Nothing fancy going on with this tiny one https://eleshop.eu/vapour-phase-mini-condens-it.html, looks a bit like a fryer .

[MagicSmoker]

Meh... How Hard Can It Be? At risk of angering the EE gods with that dreaded phrase, vapor phase reflow really doesn't seem like brain surgery to me. The only real tricky aspect I can see to constructing one is to dish the top of the lid upwards so that condensed vapor flows off the sides rather than straight onto the board. Another caveat is to vent the container through a reflux condenser to maximize the recycling of what is undoubtedly a very expensive solvent. Given the quality of work the OP has achieved in the past I don't see this being too much of a challenge for him.

Holy Frijoles - this stuff is expensive: https://www.appliedthermalfluids.com/home/shop/galden-hs-240-vapour-phase-fluid/

$1580 for 7kg?!?! You gotta do a lot of boards yourself to justify that kind of cost!

[spongle]

Did you check out my link? $75 for 250g.

Other threads have mentioned unavoidable losses around 1g per cycle, obviously more for a sloppy system.

[Kjelt]

 

Nothing fancy going on with this tiny one https://eleshop.eu/vapour-phase-mini-condens-it.html, looks a bit like a fryer .

Nothing fancy and your components can worst case be exposed to 230 degrees for over 4 minutes 
You should follow the reflow profile.

[MagicSmoker]

Did you check out my link? $75 for 250g.

Other threads have mentioned unavoidable losses around 1g per cycle, obviously more for a sloppy system.

I didn't before, but now I have and hey, they are located about 2-2.5 hours north of me here in Florida. Pretty good pricing, relatively speaking, and starting off at much smaller quantities, too. I don't think 250g will be quite enough for what the OP is after, but 1kg should be plenty (7kg would be downright excessive).

It's easy enough to reduce losses using a reflux condenser as I mentioned before and, besides, this stuff is apparently 10k worse than CO2 as a greenhouse gas (even high boiling point liquids like this give off some vapor at room temperature).

That said, Kjelt makes a pertinent observation about exposing the boards to reflow temperatures for too long. I'm not liking any of the ways I've come up with off the top of my head to get around this (basically involving putting the board in *after* the solvent has come up to temperature then removing it after all the paste has reflowed).

So, yeah, I guess it might be a fairly hard problem to solve and probably not worth the trouble.

[rx8pilot]

Nothing fancy going on with this tiny one https://eleshop.eu/vapour-phase-mini-condens-it.html, looks a bit like a fryer .

The size seems interesting, but I feel that having control over the PCB position is critical. I don't mind (at least initially) having a manual movement so that I can control the heat profile the PCB is exposed to without having to have some complex active cooling system.

Meh... How Hard Can It Be? At risk of angering the EE gods with that dreaded phrase, vapor phase reflow really doesn't seem like brain surgery to me.

In concept it is simple. From what I can see so far, the challenge is primarily mechanical since the system needs to be fairly well sealed under operating conditions and needs an elevator arrangement to control the thermal profile. The electrical system and PID is trivial in comparison. Getting PCB's in/out of the system while the galden is still hot needs a relatively complex/clever arrangement.

I like the idea of starting with some sort of existing commercial kitchen appliance that I could modify and construct an elevator. Something fairly tall would be nice. Since I have a CNC machine shop and a lot of motion control experience, it is doable. i would say that half of my motivation is necessity and the other half is doing something fun and unique. The goal is not specifically to be ultra-cheap or to make a business out of it.

[spongle]

Getting PCB's in/out of the system while the galden is still hot needs a relatively complex/clever arrangement.

I am thinking now about having auxiliary reservoirs for preheating/chilling the galden.

If coupled by steel flex hose, they could be raised/lowered by an external mechanism to transfer the liquid, or have fixed positions and use ball valves to dump the hot galden into the main chamber and drain it for cooling.

However, this might be unnecessary if enough cooling power can simply be applied to the fluid with a copper water coil or similar.

[OwO]

Is vapor phase really necessary at all or do you just simply need a fan in your oven 

[Kjelt]

Is vapor phase really necessary at all or do you just simply need a fan in your oven 

My opinion:

- an IR radiating oven ( that is the one I have) has a major disadvantage that it is direct heat to the parts, some parts mostly connectors don't like that at all and can melt.
- an conventional oven with (non IR) heating elements is too slow, it can not follow the reflow profile IMO.
  it takes too long to heat up to the desired temp and when there it takes way too long too cool down again.

So the pro's solve this to place multiple ovens on multiple temperatures behind eachother in a line so the reflow profile is matched.
Hobbieists can either go for IR oven and in case of connectors they have to shield them, or vapor phase.

[OwO]

Yes IR ovens are 💩.

I don't see why it isn't possible to simply use hot air in an oven to get fast heating and cooling, the air intake can be from inside the oven during heat up and outside during cooldown. Or simply an oven with a fan and vent port for cooldown. Either way it should be easier than building an airtight chamber and using dangerous and expensive fluids.

[spongle]

Actually, Galden is quite safe, you can even ingest it without harm. It's only a danger if you get it above decomposition temperature, certainly quite a lot better for you than breathing the exhaust fumes from a convection oven...

In addition to the intrinsic temperature limiting to prevent component damage, VP provides very even heating, excellent heat transfer for component with high thermal mass, and shields the board from oxygen (vapor displaces the air) for better solder joints.

[Kjelt]

I don't see why it isn't possible to simply use hot air in an oven to get fast heating and cooling, the air intake can be from inside the oven during heat up and outside during cooldown.

If you have a tiny oven that might succeed, if it is a normal size pizza oven you will not get an even temperature distribution unless you put a 8kW heater with large blower on it and then the airflow will blow off the components.

[helius]

Without heat control, vapor phase will not achieve good results. The vapor cloud does not have enough heat capacity to reflow the board; it is only a small heat reservoir between the liquid heater and the components. The reflow profile is programmed, just like with a convection heater.

[Koen]

I use a cheap asparagus cooker, a cheap hot plate and a small bottle of Galden. 40 boards a week. Easy, cheap, reliable, perfect not to melt connectors. I switch between asparagus cookers. One cools down, one heats up.

If I wanted to do more, I'd buy a big deep rectangular stainless container. The stuff in which massive kitchen cook vegetables and put it on the same cheap hot plate.

[spongle]

Do you do anything to calibrate the temperature of your hot plate? Or is it just "set and watch", and pull off the heat when you see reflow?

How are you suspending the boards above the galden, and how far above?

[Koen]

I stack five boards in the cooker. And use a small TM-902C thermometer to monitor it. It's all very easy and convenient.

There's a small hole in the asparagus cooker lid that fits the thermometer probe perfectly.

[rx8pilot]

I use a cheap asparagus cooker, a cheap hot plate and a small bottle of Galden. 40 boards a week. Easy, cheap, reliable, perfect not to melt connectors. I switch between asparagus cookers. One cools down, one heats up.

If I wanted to do more, I'd buy a big deep rectangular stainless container. The stuff in which massive kitchen cook vegetables and put it on the same cheap hot plate.

This the first level of experimenting I am expecting to do. Hoping to gain some knowledge of the process nuances by trial and error before I get any expensive parts.
Looking around for common items that can be repurposed for the heating chamber, lift, etc.

[mrpackethead]

Moving the boards is possible but you'll have to do it very gently.. Any bumps etc will result in displaced parts.

My experince, is that you can get good temp control with just heating up the galden with enough heat.   The IEMS i had did'tn have enough capacity to heat up quick enough.
Cooling is the more tricky thing.  However i've foudn running cold water through a some stainless steel pipe coiled in the bottom of my tank works pretty well,  trying to air cool the tank like the IEMS does' results in a long cool down period.. ( way too long )..      I just send the water to the drain,  you only need a few literes per cycle..

At the simplest however a pot on a hotplate is all you need.

[Kjelt]

Reading this you wonder why the pro machines have:

- Height controlled platform with multiple temperature sensors feedback
- Active cooling
- Galden recovery (vacuum/suction)
- Double lids, one on top of the entry/exit/cooling chamber and one closing of the heating/Galden chamber.

such a waiste of materials 

[SMTech]

I think little units from the likes of Roland Hecht (who are no longer?) Exmore & Asscon (some of which may be the same unit) use a built in ballast for the cooling. Incidentally the 1g/cycle number I have used previously came form a Roland Hecht daatasheet (or their sales representative).

Big machines are plumbed into the water supply.

[mrpackethead]

I think little units from the likes of Roland Hecht (who are no longer?) Exmore & Asscon (some of which may be the same unit) use a built in ballast for the cooling. Incidentally the 1g/cycle number I have used previously came form a Roland Hecht daatasheet (or their sales representative).

Big machines are plumbed into the water supply.

iv'e processed about 1200 panels ( approx A4 ) size  and used aprox 900ml of galden.   The galden does'nt pour out the top of the tank. It does'tn dissapear when its cold.  It is quite hydroscopic and the first cycle you do, quite often will produce quite a bit of steam which will try to escape.