Vapor Phase reflow oven

[hobbyelectronics]

Hello,

I know that the Vapor phase reflow topic has been discussed a fair bit, but I have specific question.
Does anyone on here have the Vaporflow 275 vapour phase reflow oven?

https://www.vaporflow.eu

https://eleshop.eu/vaporflow-275-vapour-phase-reflow-oven.html

At work we purchased a Imdes mini which we purchased specifically for making just a few prototypes.
https://www.imdes.de/produkt/mini-condens-it/?lang=en

I used this to produce maybe 100 plus board which all came out perfectly. I was amazed. No tombstoning , no issues at all. Boards were about 50x80 in panels of four with about 100+ components, mainly 0603, SOIC and connectors, nothing too demanding.

I would like to buy a Vapor phase oven to use for prototypes and small production runs (Maybe 100 boards per month).
I just want to hear from anyone who has one of the Vaporflow 275 ovens, and to see what they think of it.
It seems a lot of money for almost hobby use. Or do I make my own??? LOL

Thanks
Paul

[hobbyelectronics]

Hi,

Basically I just want to find out if for the cost of the VaporFlow 275, is it worth it?
Only really seems to be two options (Manufacturers) for a budget unit (Compared to commercial units) that are available.

Thanks
Paul

[glenenglish]

Hi Paul
I have a three  IMDES MINI machines . very good.

I'll never go back to using an oven ever. My boards 8-12 layers, BGA, never ever had a issue...
always SAC305, 230degC Galden.
Dont let the fluid be too high- dont fill higher than the provided gauge measure.

How much is the Vaporflow 275

[woody]

Hi,

I own a VaporPhase 275 since the end of 2022. It is a well-built device that I use for prototypes and very small runs of existing designs after changes in hardware. Before that I used a pimped-up toaster oven (isolation, controller)

What I like about the 275 is the set and forget aspect. I just shove a board in, start the fume extractor and the solder cycle and come back 10 minutes later to find it soldered. I never see tombstoning. I do see solder balling, but that has to do a lot with the type, age (water content) and amount (thickness of stencil) of paste used and with temperature profile. The default profile is a bit too quick IMO. OTOH, solder balls are easily removed using a (EDS safe) brush so not a real problem. Solder balls usually appear next to 'larger' components like C's and R's, and not next to .4mm pitched IC's.

A year in I find that the 275 was certainly worth the money, as it makes the solder step in my workflow a lot easier and predictable than it used to be. If it breaks I'll buy it again (after a discussion with Eleshop .

When I got it there was no VaporFlow 480 which for my use was no issue. But if you use the oven to make a hundred PCB's per month the 480 probably makes more sense.

Paul

[hobbyelectronics]

Hi Paul,

Thank you for your reply, I really appreciate it. Its really good to hear from someone taht actually owns one. It strange because their does not seem to be any reviews online or on YouTube etc.
Its good to hear that its a well built machine and works well. I think for me the 480 is just too costly for what I would use it for, the 275 is also slightly higher than I would like to pay, but at a push, I would get one.
Can I ask a you few questions.

1, When creating a custom profile, is it limited to the number of steps you can enter? I can see that you can create steps to end on a temperature endpoint of a timed step but is is limited to how many steps you can have for one profile?
2, If creating a cooling step, can you enter a percentage power (or speed) to the fans, such a 80% or is the fan control limited to simply on or off? I assume you can end a cooling step by time or a temp setpoint.
3, I believe the 275 only has one TC inside the chamber. How far above the bottom is it and typically how far above the top of the LS230 fluid is it, and lastly, how far is it above the wire rack is it?

oh, one more question what fume extractor do you use with it? I would certainly need one as well!

I hope you don't mind me asking. Its would be great for me to know this.

Thanks for your time. I think this will help me decide if I will buy one or not.

Regards
Paul.

[law]

Hi Glenn,

Can you recommend a seller for the Imdes Minis?

Thanks

[glenenglish]

I purchase direct from IMDES and fedex it.
No reseller is going to be able to offer any value (of  being a reseller )

[hobbyelectronics]

Hi Law,
At work we we purchased it from eleshop.eu, but I don't think they sell the IMDES mini any more.
They have the VaporFlow 275 available for more or less the same price.

From what I have seen and read, the VaporFlow 275 'may' be a better option?
The IMDES we have has worked perfectly for us. The results were excellent, far better than what I originally expected.
Actually, we had one issue, that the main power switch failed after a year or so. Which is not a big issue really.

Thanks
Paul

[trevwhite]

Do many people get drips of Galden on their boards after it’s finished? The only hassle for me is the boards are not dry when finished. I have a Imdes Jumbo. I would not say the build quality is professional but it works. The VaporFlow looks like it might be made better.

[woody]

Do many people get drips of Galden on their boards after it’s finished? The only hassle for me is the boards are not dry when finished. I have a Imdes Jumbo. I would not say the build quality is professional but it works. The VaporFlow looks like it might be made better.

Yep, my boards are not completely dry either. I cannot say if these drips are coming from 'above' (the lid) or are the result of some uneven cooling of the PCB that results in the condensation of Galden on it. I remember that when I visited Imdes a couple of years ago that they were working on a sort of 'runoff ramp' attached to the lid to make condensation on it run to the side and not rain on the PCB. I don't know if that ever made it into production.

The VaporPhase I have does not have a provision for that and I suspect that that might the reason for the (few) drips I see on the PCB. Not a big problem; wiping with IPA takes care of it. Although one might reason that every drop costs at least a Euro.

[glenenglish]

I allow with extra cooling cycles so that the chamber can  get below 45 C before I open the lid, I allow the galden from the lid to drain vertically into the soup...... boards are not too wet.

[woody]

1, When creating a custom profile, is it limited to the number of steps you can enter? I can see that you can create steps to end on a temperature endpoint of a timed step but is is limited to how many steps you can have for one profile?

Not that I can see. Contact Eleshop with this question, they wrote the firmware.

2, If creating a cooling step, can you enter a percentage power (or speed) to the fans, such a 80% or is the fan control limited to simply on or off? I assume you can end a cooling step by time or a temp setpoint.

Yes, you can enter a percentage for cooling power. The result is that the fans run slower, albeit a bit 'erratically': switching on and off. It is that you asked, I never used this feature before, all my cooling is at 100% You have to take into account that cooling is difficult with these ovens. I created a custom profile to better imitate the soaking stage of a solder profile to prevent the aforementioned solder balling. This turned out to be quite difficult, as the system heats up long after the heating elements are switched off.

3, I believe the 275 only has one TC inside the chamber. How far above the bottom is it and typically how far above the top of the LS230 fluid is it, and lastly, how far is it above the wire rack is it?

Yes, one TC in the chamber, maybe 4 cm above the bottom. You typically only have a couple of mm of Galden in the tank. The wire rack is some 1.5mm above the bottom. For precise measurements, contact Eleshop.

oh, one more question what fume extractor do you use with it? I would certainly need one as well!

https://eleshop.eu/fe1bd-esd-safe-fume-extractor.html

[trevwhite]

For me the wetness is the only thing I hate. Remember if that is Galden then wiping it away is costing money.


Be nice to come up with a solution between us all for that. I think the better machines lift the board out of the vapour cloud to stop them getting wet. Any high temp solution to enable the board height to be adjusted inside the oven? Maybe that would solve a lot of issues.

[woody]

I allow with extra cooling cycles so that the chamber can  get below 45 C before I open the lid, I allow the galden from the lid to drain vertically into the soup...... boards are not too wet.

Same here. But even after extended cooling they are not completely dry.

[glenenglish]

take them out when they're 45-52C and the galden evaporates off.....

[trevwhite]

I have left them in a long time and there are still puddles of Galden. Maybe its drips from the lid in that case? I might try and sloped piece of glass attached to the underside off the lid.

[woody]

Be nice to come up with a solution between us all for that. I think the better machines lift the board out of the vapour cloud to stop them getting wet. Any high temp solution to enable the board height to be adjusted inside the oven? Maybe that would solve a lot of issues.

Certainly. I think that maybe a runoff on the lid is not a bad idea. A simple piece of folded aluminum might do the trick. That way the inevitable condensation on the lid does not end up on the PCB. Drops during the process evaporate again but drops during the cooling phase might not.
As for VP ovens that lift the PCB, yes, that might be a better solution. I looked at such a solution (https://shop.pcb-arts.com/products/vapor-phase-one). Very nice but complicated and for the price difference with the 275 I could get at least 3 gallons of Galden. I am now still only halfway though my first 500 ml bottle. For my use this is the best solution.

[hobbyelectronics]

Just out of interest, how do the commercial vapor phase ovens overcome this small problem of boards still having some Galden on them.
Do they go through a wash process, or air dryer?

At the end of the day, as the boards are horizontal, will they always have some condensed fluid on them?

With regard to the vapor escaping out of the lid, would have a taller chamber help, so hot vapor would never reach the top of the chamber. It would cool down and condense before escaping?

[woody]

If I ran a VP production line I would save as much Galden as possible. Most commercial ovens I have seen (from afar, not from working with them) do have lifting systems, or even doors that open and close in the chamber. As well as cooling systems.

As I remarked, there is a 'cheap' VP oven with lifting and cooling, but I found that a bit over engineered and a bit too expensive when I compared it to the Imdes or the VaporFlow.

Vaporphase soldering is based on the properties of Galden fluid. Basically all you need is a pot and a hotplate (as demonstrated in various Youtube examples). Having some temperature control to make sure you reach soldering temperature at PCB level is nice and a system to prevent 'dry cooking' is important (as heating Galden above 300 deg is dangerous) but apart from that this is not rocket science.

Higher chambers will help, but hot vapor will always reach the lid; Galden attracts water and some steam will escape. The same goes for the vaporized components of the solder- and flux. In my experience you hardly lose any Galden using the VaporFlow. For me investing in elaborate cooling and lifting systems makes no sense for the prototyping and small series production I do.

Paul

[SMTech]

by being larger and having moving parts. The vapour zone sits at the boom of the tank and doesn't extend to a surface the galden could condense on and then drip back on the board. The baords are lowered into the vapour zonestay there until they reach temp and then are raised out again, There will typically be an assisted cooling and drying phase ->IBL have this presentation or you could lookup Asscon.

[glenenglish]

you can make a good system from
1) some deep stainless food tubs from a catering store ' Gastronorm food tray' or food pan  . like 300mm deep , and they come with lids
2) some high temp thermal epoxy attach a handful of   ceramic heating  blocks  on the bottom
3) say 4 to 8 thermocouple probes at different heights to figure out what your doing.,
4) half a dozen muffin fans to cool it fast.
5) A coil /grid of stainless tube about a couple of inches from the top (attach to lid) circulating water  to create a condense cool  zone below the lid.
6) A basic PLC or Arduino to drive it all

Option- braze a coil of copper/stainless tube around the lower part of the dish to circulate water to improve cooling rate.

[hobbyelectronics]

That sounds pretty good.
I did develop a Peltier heating / cooling system for work, which used multiple Peltier elements and a temp controller to test some devices. Which worked really well. They have been running at a few degrees, and also a heat cycle up to around 85 deg. Been running daily for nearly two years without any problem. Seem to be pretty reliable, once you understand the concept. I blew up a number of elements during the development

These could also be attached under a vessel, and around the sides and used to heat and cool at a controlled rate. Cooling Peltier elements around the top could also be used to create a cold zone.
The Peltier elements could be bonded directly to the vessel, or  have a clamping arrangement so they can be replaced if needed.

Maybe, IR lamps below the vessel, at least with Halogen lamps, they have no (low) residual heat and can be turned off quickly and heat up almost instantly as well.. Running a couple of 1KW tubes with proportional phase control (0 to 100%) and PWM a bank of fans for cooling.

just some thoughts really.

[Doctorandus_P]

From what I heared those vapor phase things work pretty well, but I still do believe they are horribly overpriced.

The oven itself it not much more then a standard food dish (chafing dish?) as used in the horeca and those cost EUR50 or less, including the lid. Slap on some heating elements and a bit of simple electronics and you're almost finished.

My second gripe is with the cost of the fluid. EUR200 per liter is quite expensive for fluid, and I suspect it is similarly overpriced like the oven itself.

And what really kills the last interest is the way the oven is built. In the video they add an (External!) fume extractor (They can't include that for that price?). If the liquid is really that expensive, you also want to recoup as much of it as you can. That means making the fume extractor internally to the heated area, and add a heat exchanger to cool the extracted fumes so the galden fluid gets recycled back into the system.

Here is an alternative: Get a pressure cooker and use simple water / steam as the medium. Disadvantage is you would need a pressure of around 5MPa and that makes the pressure vessel a bit expensive and dangerous (Such things need to be certified).

I also just had a look a Glycerol. It's boiling point is 290c, so a bit high. Maybe it works under a partial vacuum, or you can try to find some other affordable liquid with a suitable boiling point.

Maybe re-visit Marco Reps. He built his own vapor phase oven and made a youtube vid about it a few years ago. I'm not sure whether he made a follow up with his experiences thus far.

[wraper]

Hi Glenn,

Can you recommend a seller for the Imdes Minis?

Thanks

It's an absolute garbage with terrible electrically unsafe electronics, non working overheat protection (there is a thermal switch but it's mounted in a way that renders it useless), and terrible reflow profile. Without changing the controller I consider it borderline unusable. I'm surprised OP did not have tombstoning issues. Not to say it's assembled with pop rivets, making it impossible to non destructively take apart.

[glenenglish]

It's an absolute garbage with terrible electrically unsafe electronics, non working overheat protection (there is a thermal switch but it's mounted in a way that renders it useless), and terrible reflow profile. Without changing the controller I consider it borderline unusable. I'm surprised OP did not have tombstoning issues. Not to say it's assembled with pop rivets, making it impossible to non destructively take apart.

Yeah, I would agree with that ! I did modify my controllers.  All my IMDES controllers all had different profiles.....

[hobbyelectronics]

On a side note but still about vapor phase, what would be considered the best solution to control the heater, assuming its powered by 230VAC?
To control the heater with a percentage power in the profile control itself, for each step, PID control would not be required.

Some of my thoughts are:

1, SSR with Zero crossing. (Perhaps, changing the on/off ratio over 1 second, giving maybe 0 to 100%, e.g. on for 200 mS, off for 800 mS to give approx. 20%)
But with a zero crossing SSR the switch on time could be up to 10 mS, depending where it is in the AC cycle. (Do they also switch off at the zero cross over?)

2, Same as above but maybe use a zero crossing detector circuit so that a normal non zero crossing SSR is turned on and off close to zero volts.

3, Use zero crossing detection, then fire a TRIAC to give phase control, so each profile cycle could give the correct percentage of power for each heating step. (e.g., 80% heat. For either a timed step or temperature endpoint is reached)

4, Use a TRIAC instead of a SSR but trigger it with a zero crossing opto (Such as MOC3083M with built in ZCD), but still use on/off times over one or 2 seconds. So the TRIAC is only fired at zero, but the ratio is controlled by the on/off times.

5, Simple mechanical relay with varying on/off times over a few seconds.

6, Any other method to control proportional power, maybe FETS, or another way.


I am very interested in this and may cobble something together as an experiment, maybe use a small custom ARM or PIC based controller with a small display. Perhaps driving either Halogen heater tubes (2x 500W) or maybe a 750W Silicon heater mat.
Any thoughts on this or ideas about mains proportional power control would be interesting.

Thanks

[wraper]

Just t show what sort of garbage IMDES is.

[wraper]

There are multiple old threads on this forum about vapor phase, but what worked for me when modifying mini condens is described here, you may want to read more of that thread.
https://www.eevblog.com/forum/reviews/mini-blog-imdes-vapour-phase-purchase/msg1104140/#msg1104140

[andrea.longobardi85]

by being larger and having moving parts. The vapour zone sits at the boom of the tank and doesn't extend to a surface the galden could condense on and then drip back on the board. The baords are lowered into the vapour zonestay there until they reach temp and then are raised out again, There will typically be an assisted cooling and drying phase ->IBL have this presentation or you could lookup Asscon.

I wander what is the price gap between a professional Vapor phase as an IBL and the vaporflow…
Another question I have…what is the drawback of a Vapor phase oven compared to a convection reflow oven beside maybe throughput…as far as I understand Vapor phase consume less energy, require less space and the thermal stress on components is lower…

[SMTech]

by being larger and having moving parts. The vapour zone sits at the boom of the tank and doesn't extend to a surface the galden could condense on and then drip back on the board. The baords are lowered into the vapour zonestay there until they reach temp and then are raised out again, There will typically be an assisted cooling and drying phase ->IBL have this presentation or you could lookup Asscon.

I wander what is the price gap between a professional Vapor phase as an IBL and the vaporflow…
Another question I have…what is the drawback of a Vapor phase oven compared to a convection reflow oven beside maybe throughput…as far as I understand Vapor phase consume less energy, require less space and the thermal stress on components is lower…

I don't have up to date numbers but based on old quotes, an top loading machine like a VP 510 should be in the €20-30K bracket, the IBL perhaps at the higher end of that range. That is still just a batch reflow oven, for the same money you can get something forced convection that can handle continuous throughput. Inline VP does exist but it is quite expensive and might need things like water supply for cooling. You will find a number of Electrolytic capacitor datasheets tell you not to use vapour phase reflow as they suffer damage and capacity loss.

[andrea.longobardi85]

Thanks, indeed I have seen also SMD sensors that could not been soldered with Vapor Phase…

[glenenglish]

Andrea : The sensors that could not be soldered- did they not have tape over the sensor port ?

The IMDES yes, you do need to do some modifications.  . I cut a slot in the PCB between those two pins- note :  my 1st IMDES was like that, but my 2nd IMDES had 3mm spacing. I pointed this out to them and they modified it.

But the basic idea works well.

What the IMDES experience shows that even if you do a sh1t job at implementation, results are still quite good.

[Doctorandus_P]

What the IMDES experience shows that even if you do a sh1t job at implementation, results are still quite good.

Yes, of course it is.
The soldering quality is mostly guaranteed by the boiling point of the fluid (which is a pretty stable temperature), and the energy release when the vapor condenses on your PCB. Oxygen displacement is also inherent in the process, and even pre-heating is done by holding the PCB horizontal when the hot vapour rizes. (This fluid has a lot of gravity in it, and I guess the vapor is also quite heavy)

Because (nearly) the whole process is controlled by the fluid and it's vapor, the machine itself is a very simple thing, and that is why it's just a horeca pan with a heating element, with a few extra considerations:

1. You do not want to over cook the vapor. When it decomposes because of over heating you get nasty gasses.
2. You want to reclaim as much of the vapor / fluid as possible, because the stuff is expensive. (And those EUR1500 ovens do a pretty mediocre job at that).

[hobbyelectronics]

I am so tempted to build my own. I have pretty much all the parts, including a stainless tank, but its a lot of effort and time.
I am also considering buying the VaporFlow, but feel put off by the cost for what you actually get. Yes is an out of the box solution, but its still a lot of money for what it is and for small volume or hobby use, its not cheap at €1,595.00 Plus carriage at around €70.
it would be good to try one as their does not seem to many first hand reviews about it.

I used to have a UniFab 6 zone top/bottom IR oven, proper production unit, but it was so problematic. It worked, but for different boards it needed a lot of tweaking and tomb stoning was always a problem, no matter what I did.
Would be nice to have a VaporFlow, small, low hassle and hopefully as good as or far better than the IMDES (From a soldering point of view).

As these small ovens loose vapor/steam, what spec does a fume extractor need to be?

[trevwhite]

I didn’t have time to build my own. I learnt a lot from buying an Imdes oven. I learnt I was over thinking how to build my own. That oven has 400w or 800w heater that it switches on and just measures the temperature. When it gets to a certain temperature it might half heat on. It holds temp for a while and then switches fans on to cool everything down. That’s about it. You won’t be getting much more than that for your money.

[hobbyelectronics]

Yes, that is so true, its a lot of money for what you are actually getting. However, it depends on if you need a vapor phase soldering solution. Then the lower cost options are limited to maybe two.

My thoughts, were to control the power with phase control (say 0 to 100%), and PWM the fans (5 to 100%), either have two halogen heater tubes (500W each) or a silicon heater mat and have a touch screen for the control.
A simple method to edit / create the profile in steps. Each step would endpoint with temperature or time and be either cooling or heating, with a percentage value for power (Heat or cool), when the step endpoint is reached (time or temp) it moves to the next step.
That way the control could be pretty good, with multiple steps I think you could achieve a good temperature profile.

And perhaps with a keep warm function, maybe to just keep the fluid above ambient, for faster throughput.

Maybe some sort of better lid / cooling design to try to minimise the loss of fluid.

Just thoughts really.
Maybe convert an ultrasonic tank/bath unit. They can be about the right size and have lids and picked up fairly cheap.
I am surprised that their is not a low cost, maybe smaller, version available aimed purely at hobbyist. I think it would really work. Could be fairly small really.

Interesting. I did look around to see if stainless tanks are available off the shelf that may suit, but not found much.


Interesting, what's available:
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2332490.m570.l1313&_nkw=untrasonic+tank&_sacat=0

[ace1903]

Interesting approach using deep fryer  shown on video on YT
https://youtu.be/jiEU2uqPdsE?t=1531
I am also overthinking solution with special heaters and cooling system.
Seems that deep fryer with PT100 sensor and on/off control will do the job perfectly.

[woody]

I didn’t have time to build my own.

Same here. I started to realize that, while I might be able to make anything (within limits) it sometimes makes more sense to just get an acceptable solution and start using it. Most aspects of a VP oven are relatively simple as the smart is in the fluid, and it would not be too complicated to build one, but buying one enabled me to solder right away. I never looked back.

Then again, everybody's miles, dollars and entrepreneurial instincts vary.
 

[wraper]

Interesting approach using deep fryer  shown on video on YT
https://youtu.be/jiEU2uqPdsE?t=1531
I am also overthinking solution with special heaters and cooling system.
Seems that deep fryer with PT100 sensor and on/off control will do the job perfectly.

Modifying deep fryer should be fine IMO. However you must not use something with immersible tube heater as it will require a ridiculous amount of extremely expensive Galden and thermal inertia will go through the roof too. You want cooling BTW, otherwise it will cool down forever and more Galden will be lost.

[trevwhite]

Whilst the Imdes build quality is questionable I think the oven works and for that reason I would copy its construction as a starting point. I would build one for immediate use and another for experimentation.

It really is a simple oven and it works okay, especially for hobby use.

[hobbyelectronics]

Whilst the Imdes build quality is questionable I think the oven works and for that reason I would copy its construction as a starting point. I would build one for immediate use and another for experimentation.

It really is a simple oven and it works okay, especially for hobby use.

Yeah, all very true, the Vaporflow is not cheap (Or the IMDES), but its an out of the box solution - That works.
And, I still have to say the IMDES Mini we purchased in work just to do a few boards, amazed me. The results were incredible really. Nice shiny joints, that looked spot on. Had no issues at all with the actual finishes boards.

LS230 is magic!.

[trevwhite]

Vapor phase really is magical stuff. It's a very clever solution ( pun intended ).


I was drawn to it because one profile works for any size/density of board.

[sam512bb]

Good day All,

I do not know if anyone found this past , but dated, thread on VP:

https://www.eevblog.com/forum/projects/vapour-phase-soldering/

I thought it might be of interest.

Cheers,

Sam

[glenenglish]

Interesting thing happened recently
I had identical boards in two IMDES machines . In one VP  oven,  the hermatically sealed relays (10mm long, 5mm tall, 8 mm wide, quite light weight )  seemed to float off the PCB onto other areas of the PCB - they moved about 20mm....
The Galden level was higher  (and 50%  higher than the depth probe they give you)  than the one that had no problems, I'm putting that down to some bouyancy occuring in the process.
Have not investigated much yet on that apart from noticing the levels was higher. fix the galden level, and my relays stopped floating.

[hobbyelectronics]

That's interesting info, thanks.
I assume the the top of the liquid was still below the PCB?

One thing I did notice is that with the imdes we have at work, we never measure the liquid level, just pour it in and hope for the best.
Its never changed the out come of the boards. But then we never placed sealed components that may have air inside and could maybe move around more easily in the dense vapor???

Looking at the measuring stick that is supplied with the VaporFlow, you really don't need much liquid in the bottom of the chamber. Looks like its only a few mm. They also give a figure in grams and ml I think as well as the measuring stick.

Out of interest, we use very fine micron, metal disposable paint strainer to filter the fluid (like a coned coffee filter and much cheaper). We also clean the tank when we empty the fluid to filter it.

[jpanhalt]

Voted based on my very limited experience with a T962(modified).  A VP reflow would have to get ready to run fast and be stable for long periods of non-use.  It would have to be clearly better than my T962 that I got new for $100.

[woody]

Out of interest, we use very fine micron, metal disposable paint strainer to filter the fluid (like a coned coffee filter and much cheaper). We also clean the tank when we empty the fluid to filter it.

May I ask, how often (in relation to how often you use the oven) do you clean the Galden fluid?

[IconicPCB]

Do any oven manufacturers specify volume of liquid versus resulting volume of vapor?

[wraper]

Do any oven manufacturers specify volume of liquid versus resulting volume of vapor?

There is no such thing, garden must never evaporate entirely. If it happens, Galden will overheat and decompose into highly toxic hydrogen fluoride https://www.dir.ca.gov/dosh/dosh_publications/Hydrogen-Flouride-fs.pdf and Fluorophosgene .

[IconicPCB]

It is well known that Galden fluid is thermally liable, but that was not in question.
The problem is to determine the absolute minimum volume of fluid in an oven.

[Doctorandus_P]

It is well known that Galden fluid is thermally liable, but that was not in question.
The problem is to determine the absolute minimum volume of fluid in an oven.

There are two important factors here.
First, it's "vapor phase", i.e. It's the vapor (and thermal energy in it) that does it. not the liquid, and the liquid (and I assume vapor too) is quite heavy, so you would need to fill the volume between the bottom of the pan upto just above the PCB with saturated vapor. Air is 1.2kg/m3, so assume it's twice as heavy as air and you need 5l then you will need 12gram of this stuff.

The second important factor is that you do not want to overheat the vapor. The easiest way to achieve that is to keep the heating element itself submersed in the liquid. The liquid will keep the heating element at the boiling point of the liquid. When the heating element boils dry (too less fluid) then it will get hotter, and there is a risk the galden fluid / vapor starts decomposing (and that is a very unhealthy thing, there is fluor in there).

Normally the pan has a flat bottom, and you need to cover the whole bottom with fluid, but there is no real need to. The bottom could be bent, with some kind of float switch near the lowest point (with the heating element).

Additionally: There is not much reason to filter the fluid. (As some seem to do) Any solids in the fluid will not evaporate and simply be left on the bottom. The galden fluid could become contaminated with other liquids (Flux, or cleaning fluid residue) but those won't be easy to filter out, and probably also do not matter much. Maybe you could use distillation to get rid of them. The Vapor phase thing itself is already a heater so heat it until 10 or 20 degrees below the boiling point, and then blow away the vapors that do come out. (Also such vapors also tend to be lighter, so they have a tendency to be in a "less harmful" place anyway. The high specific density of the galden stuff has an influence on quite a lot of things...

[wraper]

here are two important factors here.
First, it's "vapor phase", i.e. It's the vapor (and thermal energy in it) that does it. not the liquid, and the liquid (and I assume vapor too) is quite heavy, so you would need to fill the volume between the bottom of the pan upto just above the PCB with saturated vapor. Air is 1.2kg/m3, so assume it's twice as heavy as air and you need 5l then you will need 12gram of this stuff.

From quick googling:

For this Galden type we can ballpark the vapor density at 260 °C (assuming 1 bar here) to be somwhere between 24 and 30 kg/m³. Galden HS260 has an average molecular weight of 1210 a.m.u, or a molar mass of 1.21 kg/m³. Applying the ideal gas law

(where p: pressure; M: molar mass; R: gas constant; T: temperature)
yields 27.3 kg/m³ at 260 °C. That's within the range I identified in that plot up there, so I guess it's ok to just apply the ideal gas law to Galden to figure out the vapor density (this is not necessarily a given). For the LS 230 grade, the result is 24.4 kg/m³ at 230 °C. For comparision, air has a density of about 0.7 kg/m³ at that temperature.

[wraper]

Additionally: There is not much reason to filter the fluid. (As some seem to do) Any solids in the fluid will not evaporate and simply be left on the bottom. The galden fluid could become contaminated with other liquids (Flux, or cleaning fluid residue) but those won't be easy to filter out, and probably also do not matter much. Maybe you could use distillation to get rid of them. The Vapor phase thing itself is already a heater so heat it until 10 or 20 degrees below the boiling point, and then blow away the vapors that do come out. (Also such vapors also tend to be lighter, so they have a tendency to be in a "less harmful" place anyway. The high specific density of the galden stuff has an influence on quite a lot of things...

IME after reflow cycle galden becomes muddy but not for long. Soon all of the contamination deposits on the metal surface. So unless you filter it ASAP after every reflow, it's completely pointless. Also amount of contamination highly depends on solder paste used. LOCTITE GC 10 causes a lot of hard to clean dark deposits on all surfaces and oven will soon look like brown shit, also it results in oven pan having strong burnt smell. On other hand Chipquick SMD291SNL and AIM M8 SAC305 cause barely any contamination and no awful smell.

[Doctorandus_P]

You did your homework better then I did, but overall, it's not the important question.

More important is what causes loss of the galden fluid, and how do you prevent it. This site: https://www.vaporflow.eu/ mentions a loss of 2 to 3 grams per cycle (Depending on oven size) And with EUR200/kg this is 40ct to 60ct per soldering cycle. It also states it needs a minimum of 290gram or 750gram to work properly (Looks like bad design to me, yuch.).

 A part of the loss is because of the liquid evaporating, which forces gas out of the enclosure, and a part of the escaping vapors will be the expensive fluid. Maybe an hermetically sealed lid can help, if it is combined with some kind of bladder that can accommodate the expansion.
Another option is to actively cool the top rim of the oven, so the vapor condenses and flows back to the bottom.

Some of the condensed fluid will also be on the PCB after soldering ended. A good way to shake it off before you take the PCB out of the oven also helps to reduce loss.

And last, there will always be some partial vapor pressure in the oven as long as it contains fluid. Minimizing the mixing of outside air with inside air when the lid is off.

[wraper]

I did not see loss anywhere close to that with IMDES mini running with my own controller that does not overcook. It can easily run for hundreds of cycles with ~50ml of Galden before I see the need to add any. The largest annoyance is that Galden condenses on the lid. But there is very little unlike with original controller. I remove it with squeegee into plastic container after each cycle so it does not drop on PCB and then pour back after finishing the job.

[newto]

Normally the pan has a flat bottom, and you need to cover the whole bottom with fluid, but there is no real need to. The bottom could be bent, with some kind of float switch near the lowest point (with the heating element).

I've wondered about that before, have a small reservoir in the middle of a sloped bottom, and then you need a much smaller volume of Galden vs for a wide area, allowing for larger (or more) boards without breaking the bank on fluid. and the heating system only needs to be around or in the bottom of the reservoir

[Styno]

You have to be very (!) careful that not all the liquid Galden is evaporated because then it's possible for the temperature to rise higher and the Galden will decompose to a very toxic gas.

[woody]

Not trying to be a wise-ass here, but IMO one should not overstate the loss of Galden in a VaporFlow like machine, which is meant for prototyping and small series. The actual loss is very low as @wraper observed. Galden is bloody expensive but even if you lose 2ml / cycle this comes to €0.45 / cycle (inc VAT). I spend WAY more on solderpaste (that I buy in 50g quantities, for larger quantities become unusable faster than I need solder paste), cleaning cloths, IPA etcetera. Galden is not going to be your bank breaker.

If the need arises to operate an Imdes or VaporFlow on a daily basis you're much better off to outsource the assembly of your boards. Also because then you are going to need a decent stencil printer, a solid PnP machine and what not. Talking about breaking the bank. Apart from this these companies are much better equipped to deal with environmental issues and part handling and acquisition than most of us are in our garages.

My take is that Imdex/VaporFlow type of solder ovens are perfect for their intended market.

[Doctorandus_P]

Not trying to be a wise-ass here...
Galden is bloody expensive but even if you lose 2ml / cycle this comes to €0.45 / cycle (inc VAT).

I think you're right. The Galden stuff is expensive, but the total cost are nor much compared with the cost of a prototype. My main gripe is not really the cost of the fluid, but more that they did not even try to conserve the fluid better oven costing EUR2000.

And for solder paste. Yes, that stuff is expensive too. Why would a price of EUR400/kg be justified if most of it is tin which does not cost much. Flux is expensive, and that I also do not understand. It's mostly quite simple chemicals. Making balls of the solder is also an easy industrial process. My main problem with solder paste is it's moderate shelf life (Except for GC10 and maybe some others). If you only do 3 prototypes per year then even a small jar takes much longer to use up then it's 2 year (official) shelf life. Has anyone tried to use separate balls and flux, and then mix a small batch of paste just before soldering a protype PCB?

And the inherent ease and reliability of this process still does make it an interesting option. But do track of your units. This Galden stuff has a quite high specific density of 1.82g/ml (for HT230)

https://www.solvay.com/sites/g/files/srpend221/files/2018-10/Galden-PFPE-Heat-Transfer-Fluids_EN-v2.2_0.pdf

And apparently it's also not only used for prototypes. The video below does look like a (smallish) production site. I like the way in which they lower the PCB's into the vapor. This way

You have to be very (!) careful that not all the liquid Galden is evaporated because then it's possible for the temperature to rise higher and the Galden will decompose to a very toxic gas.

.
Yes, indeed A decent overheating detection and automatic turnoff is mandatory. But this still makes such an oven just a horeca pan (with a glass lid), a heating element and some electronics which includes the overheating detection. If I were to build such a thing. I would add at least two temperature sensors and also turn the thing off if the difference between them becomes to big. (Imagine a damages sensor, wiring or a sensor falling off, etc).

I did not see loss anywhere close to that with IMDES mini running with my own controller that does not overcook. It can easily run for hundreds of cycles with ~50ml of Galden before I see the need to add any.

That seems quite remarkable. 

The largest annoyance is that Galden condenses on the lid. But there is very little unlike with original controller. I remove it with squeegee into plastic container after each cycle so it does not drop on PCB and then pour back after finishing the job.

You could make a double layered lid with a slanted inner glass plate (I think silicone sealent is up to the temperature) or some kind of roof above the PCB from a piece of glass. Another option is to simply tilt the whole oven so the drops on the lid slide to the side. I would also make some system in which I can squeegee it directly back into the oven without an extra plastic container. Every extra surface that gets wetted will cause needless extra liquid loss.

[woody]

Another option is to simply tilt the whole oven so the drops on the lid slide to the side. I would also make some system in which I can squeegee it directly back into the oven without an extra plastic container. Every extra surface that gets wetted will cause needless extra liquid loss.

That is actually a bad and possibly dangerous idea; the layer of Galden in these ovens is really only a few mm. By tilting it part of the bottom might no longer be covered in Galden, which might heat it beyond safe temperatures. For this reason I placed my oven using a level.

You cannot get away with filling it with extra Galden to still cover the bottom, as more of the medium slows the process time considerably. Longer heating, longer cooling. And, as we all know, it is bloody expensive 

[Doctorandus_P]

Indeed, tilting the oven is incompatible with the simplistic way in which these ovens are built. Yet another reason to not buy the standard overpriced oven. With only a few mm of fluid over the whole bottom, using a level to put the thing horizontal is indeed a sensible option. Are such levels integrated in the EUR 2000 oven? Does it have leveling feet?

If you build one from a horeca pan yourself, you could deform the sides to tilt the top while the bottom stays horizontal, but it would be quite difficult to do that while keeping both the bottom and top "flat". Something like this would be relatively easy in series production (with a big press and a mold to keep both the bottom and the top flat). And of course this can be incorporated if they used a custom bucket instead of a standard horeca pan.

[woody]

Are such levels integrated in the EUR 2000 oven? Does it have leveling feet?

My €1500 oven does not have a level and does have leveling feet.

Maybe a good idea for people trying to perfect the wheel here is making the leveling automatic; that way you can keep the oven level while soldering while, during the cooling phase when the heating element is switched off and there is no longer the danger of overheating the Galden, you can tilt the oven a bit to circumvent the drip problem. Would be an interesting project with a couple of motors, a controller and an accelerometer.

Meanwhile I'll just use the oven on my bench 

[Doctorandus_P]

Just realized, if you put a few mm of liquid in the bottom, then you can use that as a level. (Assuming the corners are rounded).

[glenenglish]

Another way I have heated prototype Vapour phase ovens is to use a induction cooktop- One of those single 'burner' induction cooktops, and a thick slab of ( the right sort of )  stainless as the bottom of the tank.
If its thick enough, many times skin depth (readily calculable) , the circuit board wont be bothered.

[Electrons]

what about a hotplate (i've got weller WHP1000 laying around) does it help in making a vapor reflow machine ?

another thing why no one has built the open source crowd funded Vapor-phase One . (by pcb arts) . I have yet to find the mechanical design of this thing .

Most build threats of Vapor phase reflow seem to reached dead end wonder why ?

[IconicPCB]

Glen,

I had similar idea early in the piece.
The footprint of the induction hob is quite small and the power would be quite concentrated in a small area. This presented a problem for me.
There is a certain maximum power density, I seem to recall 4W/cm^2 in order to not cause localized fluid decomposition,

So I otped out for four solid cast iron hobs in order to spread out heat uniformly. In fact i had a copper sheet between the hobs and the base plate ( a 5 mm thick magnetic stainless steel material).

I had since lost the copper plate in order to improve heater control loop.

I measure the vapor temperature at the height of top of the PCB being re-flown such that a reasonable soak and re-flow profile is obtained.
A major pain the neck... measure vapor  temperature but apply heat to the bottom of the vessel,

[Electrons]

@IconicPCB I might have understand something incorrectly about the process. In an ideal vapor phase machine what do want your heater to do ? output constant temperature (something like hotplate) and that intern will heat the liquid and protect against over-temperature , OR you want constant heatflux and to close the loop of the heater based on temperature of vapor or liquid ?

[IconicPCB]

It all starts with the process.
Preheat the solder joint to say 150C.
Hold it at 150C for a period of time.
Raise the temperature of solder to liquidus and hold at liquidus for a period of time.

Volume of vapor is the transport mechanism.

How to achieve these temperature steps?
Sense the temperature at the height of the solder joint and control heat input into the oven.
Here is a sample oven profile.
Blue plot is the temperature cycle ( 250C ),  redish plot is the heat demand ( PWM heavily integrated to show average value ) over time 20 min.

EDIT: may be there are people with commercial equipment who could post the process profile of their ovens for comparison?

[Electrons]

is the result you posted from oven you made ? did you get your oven to work and solder properly ?

I think If I want to design an automatic machine it is much work but simple manual controlled machine is fairly easy:
1. A stainless steel deep container . and place a heater inside . or instead by a French fries deep fryer .
2. Add temperature sensor first in liquid to make sure to control the heater and keep liquid at 230 to 240 .
3. add second temperature sensor in the middle of the pot ( this will need experimentation on the place) the role is to know the temperature of the vapor .
4. add a temperature sensor that will be screwed to the board to be soldered.
5. make a manual lifting system.
6. the process will be soaking pcb in the upper level on the chamber until it reaches 150 then lower to the vapor for reflow. the temperature sensor attached to the board will be displaced for the user and he will use this information to control the lifting system.
7. when reflow is done the pot will be cooled by some means ( huge fan for example or watercooler (like the ones CPU/GPU).
8. havenot decided if the pot led should be closed completely without any hole .

After looking at Vapor phase One design ( the have a 3D pdf that shows the design ) . the place heaters similar to deep fryer and wrap thermo couples around them to control the liquid temperature . they donot seem to have temperature sensors other than those
Also they seem to have a very small fan in the Led of the pot donot know why ? doesnot this allows vapor to escape if fan is off ??

[IconicPCB]

Yes the results are from my oven and it works quite well.I do need to do some further tweaking in order to reduce the thermal mass of the internal PCB support cage,

I think immersion heaters are bad juju since it may be possible to exceed 4W/cm2 power delivered into the fluid due to heating element small area.The fan is essential in providing for accelerated cooling of the solder joint,
Prolonged slow cooling will result in poor grain structure of the solder joint.

[Electrons]

do you use a sealed or open led ? or closed with some holes ?