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

[Kjelt]

iv'e processed about 1200 panels ( approx A4 ) size  and used aprox 900ml of galden.   

That is pretty good:

900ml = 1650g = €338.- so about 1,4g per board = €0,28 per board.

[nisma]

I'm passed from the tefal (similar to Clatronic FR 3587)  to Steba DF 300 fryer, the first allows 14x22cm boards, the latter A4 boards ( 20x30cm). Dimension are from memory.
Overal cost is small 150 to 200 Euro.

[mrpackethead]

While converting a deep fryer might intially seem a good idea, the immersion heater is a non starter.   If you are making frys, you have 3-4L of oil which submerges teh heater.   Using galden, you'll only have 2-3mm of galden in teh bottom of the tank.    and the heater wont' be in it. 

[nisma]

The heater and electric block is unused. It can be simple slided out. I use a heater similar to 3D printers on that i drop the galden using a 3d printed perisaltic pump.
On the outside of the inner container there is a soft copper tube used for the cooling water liquid (200/400ml) that i use for cooling down after process end.
 

[mrpackethead]

I did start with soft copper tube, because its really easy to work with.. However,   water + heat + pressure ends up resulting in quite signifincat errorision over time.. ( once temp gets over 80c )..   I see however your tube was on the outside of the tank.. I'd put mine on the inside of the tank.  I' have now replaed it with thin wall stainless steel.     Its harder to work/ costs more and is not thermally as conductive, but does'tn erode. so its pretty good from that respect.

Sorry i did'tn release you had actually built a system.. a few people have suggested using a deep fryer in the past ( complete with heater )..

This thread plus a couple of other discussions, and some practical experience has given me an idea for a very simple DIY grade system that could deliver good results.


INduction cooktop  like this ( https://www.breville.com/au/en/products/induction-hotplates/lic400.html )
Suitable saucepan to work with it, probalby something like a stock pot ), but needs somethign that has a decent sealing lid. ( ideally glass )

make a coil of stainless steel pipe to go into the bottom, and then bring the inlet / outlet out through a hole and then weld/braise it. That can just sit on teh bottom.    you'll need a couple of thermocouples..  and a way to control the waterflow.

I've seen teh induction cookers for as little as $50..       The heating side is easy.. The cooling side is a bit more tricky. 

[nisma]

I have tested the induction plate. It have 10 levels of power, I have used level 5.
Heat up time is fantastic, but as induction does packet modulation, the galden rises and sink 5cm depending if the plate transmit power or not. Level 1 is the same,  just the off interval is a lot longer. I think with 4 fans the cooling is enough if the vapour could climp higher up and water is not needed. Basically water is needed only if there is no lift and if the container z height is limited. Clearly if z height is limited, less ml of galden is needed to operate the reflow.

[mrpackethead]

My practical experience has been with a 'sealed'  ( has a lid ) static stainless steel chamber ( ie one with no active lift in/out for the pcb ) that air cooling was insufficent to get enough of a cool down gradient.         It was onoly getting me to 1.5C/sec which is just not enough ( really wanted at least 4 ).   With the water, it was really easy to cool it down nice and quick.

Some of the induction cooktops have very slow PWM rates, but are effectively continous control.   Idf you were getting a rise'sink of 5cm then somethigns clearly not running fast enough.     

[3roomlab]

anybody like to give your pencils a workout?

https://chemistry.stackexchange.com/questions/87904/thermophysical-properties-of-liquid-galden-ls-230-between-25-c-and-230-c

    boiling point: 230 °C
    density: 1820 kg/m³
    kinematic viscosity: 4.4 cSt = 4.4 × 10-6 m²/s
    vapor pressure: 453.3 Pa
    specific heat: 973 J/kg K
    heat of evaporation at boiling point: 63 kJ/kg
    thermal conductivity: 0.07 W/mK

1.8kg for 1L. assume the hobby pot is 1L. 25C to say 200C = 306kJ energy. so based on the curve, this 306kJ needs to be removed too in whatever the profile? in 5 minutes? some clever heat sunk hobby pot? wrapped when in use? uncovered when cooling down?

[nisma]

why you think of using 1L instead of 50ml or 100ml.

[mrpackethead]

as a starting point considering putting about about 3mm depth of galden in the bottom of your pot. Its all you need.

[3roomlab]

why you think of using 1L instead of 50ml or 100ml.

well hopefully it is easier to math out instead of 337ml or something

[nisma]

Theory for 100ml, the practice is different and involve setting time, heat transfer and loss from oven construction.
Ideally for setup, amplified pressure sensor with 12bit, better 14bit is needed in order to detect phase3 of vapour phase.
As you can see on the numbers below, if you multiply it with 10, the power requirement is a lot and this is the reason big VPH that can load 1 Lt of galden have 3.2Kwh heaters.
As Galden is a bit hygroscopic, the first heating to 150 degree is with reduced power in order to give the alcoholic and water contens from flux and from absorbed air the possibility to
escape. This assumes a Heating power of 1200W wile monitoring the main voltage using packet modulation as usual on heaters.

Step 1: Supply energy for heater with power 514 W in 43.3 second to increasing liquid temperature from 20°C to 150°C.
Step 2: Supply energy for heater with power 1028 W in 13 second to increasing liquid temperature from 150°C to 230°C.
Step 3: Supply energy for heater with power 112 W in 15 second to keep liquid temperature at 230°C
Step 4: Cooling liquid with speed 6.1 ml/second in 18 second to cooling hot iquid from 230°C to 120°C

This is the theory and pratice is that cooling must be doubled (thermal mass of oven heat it up again, repeated later two times for 8.2 sec) 
resulting in 270 sec for reflow and 530 sec for reaching 120 degree.
In theory, it is 71,3 sec for the reflow and 89,3 for the whole cycle.  If you make a simulation with thermal mass, thermal loss of oven construction, .... maybe you get the same
values as the reality. This cooling is fine because it is cheap and simple to do, but not for production, only for setup.

Is that what you had wanted or not ?
Basically it start at 20 deg. and need to go up to 230 deg. this are 210K temp. diff.
Now 100ml = 182 gr and , the specific heat is  177 J/K and specific heat for producing vapour is 114.66 J/ml, heating element is 1000W as assumption.
That means 230 deg. heated 100ml fluid can be evaporated with 1kwh heater in less then 11.5 seconds or 1kg in 63 seconds.
 210° * 177J = 37170J / 1000w = 37,17 sec for reaching 230 deg and then if you want evaporate 20.93ml you need 2.4 sec heating power of 1kw.

[rx8pilot]

As I was doodling some design ideas I considered the concept of moving the galden/heating element and leaving the PCB position static. The galden does not have to move as delicately as the PCB. The best part of that idea for me is the possibility of having a three-layer Pyrex window to observe the re-flow status at fairly close range. Only a single level of thermocouples would be needed at the PCB level plus one on the moving galden level. On paper, it seems like a simplified approach that reduces the complexity/precision of the mechanics.

The next consideration is a cooling system that is reasonably simple to execute. I have some ideas that don't seem too bad. Trying to get a drawing together but the basics are having a DI water reservoir (no fancy chemicals), a radiator, a pump, and a winding of copper coils thermally bonded to the main chamber. The main chamber would be wrapped in insulation and placed in a larger enclosure. Hoping this would be enough to overachieve on positive and negative temp gradients. So far - this in the territory of a single weekend to build depending on how many off the shelf parts I can identify and how much I have to custom machine/fabricate.

Still unsure how to maximize the galden recovery.

[mrpackethead]

Still unsure how to maximize the galden recovery.

where are you expecting to loose the galden?

[rx8pilot]

Still unsure how to maximize the galden recovery.

where are you expecting to loose the galden?

leaks, cracks, opening the top while still hot, etc....not really sure honestly. It just seems that the commercial designs bend over backward to get the galden back to the reservoir. Perhaps it is a non-issue.

[mrpackethead]

Still unsure how to maximize the galden recovery.

where are you expecting to loose the galden?

leaks, cracks, opening the top while still hot, etc....not really sure honestly. It just seems that the commercial designs bend over backward to get the galden back to the reservoir. Perhaps it is a non-issue.

its not a non-issue *if* you are not trying to keep the galden vapour hot and raising / lowering the pcb into it, so you can increase your throughput..   Hot galden vapour will move easily and you would loose it.    By leaving your pcb fixed in a closed container, and letting it cool down before you open it,  that issue really just dissapears and becomes a non issue.

[Koen]

Damn, try the thing with a pot and a hot plate first. I never bought more Galden. I don't feel like I'm losing any. Most condenses back in the pot.

I do filter it with a coffee filter from time to time though.

[mrpackethead]

Damn, try the thing with a pot and a hot plate first. I never bought more Galden. I don't feel like I'm losing any. Most condenses back in the pot.

yes, its a whole lot simpler than lots of people appear to be wanting to make the problem.    I'm curious though Koen,  how do you find your cool down goes?  I find that just letting it passively cool just takes too long

[rx8pilot]

  I'm curious though Koen,  how do you find your cool down goes?  I find that just letting it passively cool just takes too long

My expectation is that it needs forced/active cooling.
Also - my goal is not to do one PCB and call it a day. Hoping that it will be at least as fast as my current JEM-310 batch convection oven but offering a better final result.

[mrpackethead]

My expectation is that it needs forced/active cooling.
Also - my goal is not to do one PCB and call it a day. Hoping that it will be at least as fast as my current JEM-310 batch convection oven but offering a better final result.

My experience has been that it takes too long, in the stainless steel baine marie container i use, forced air, was just not enough too cool it down.      THats why i have experimented with thin pipe in the bottom carrying water for the cool down.   

My currnet project is to build three or four units side by side,  which will give me the capacity to keep up with the PNP line.

[3roomlab]

well here is quite a fun looking simulation
100ml of water mrpackethead?

(edit corrected error, to ml instead of grams of material)

I am guessing the pro machine must have flow controls
additional simulation, cool water rate of change @ 100ml per sec gives about 110C drop in about 9 sec.
correction, looks like only 25ml/s needed for 70C drop in 9s, much closer to the profile needs
but this is assuming the interface of water to galden is really really good
the scenario looks like the reverse of a capacitor welding machine but discharging heat !

[mrpackethead]

no, quite a lot of liters of water, running through it too cool it down.

[mrpackethead]

Been thinking about how to possibly DIY this today easiy and while i was wondering around briscoes today, i saw this.. Its an electric fry pan, its got a nice curved lid..

The galden cloud can be controlled well, and even though this has reletively low sides, it shoudl be quite possible to hold the galden in their when its hot.  Some of the soft vapour will hit the lid, but it will condense, roll down teh lid and back into the pan.          The frying pans heat control should not be too hard to hack.       Theres a vent hole in the lid, that would need to be closed, but its small.    Even if the main cloud reached the glass, it would just roll down.

A a few loops of stainless steel tube in the bottom for cooling water.   

A suitable frying pan should be obtainable for less than $100,  ( this is 2400W one, and was $89NZ ).. i could get an A4 page sitting on the bottom so it is big enough for me.   I think we probably need a coupel of thermocouples on this, possibly one attached to the base of the pan, and one a bit higher than PCB height.

Control should be easily done with something like an Adunio,     inputs would be a few push buttons,  the thermocouples..  output would be driving a Zero crossing Triac Driver, and a solinod for the water.    You might want to pump water,  so you get some variable control of flow..    Ii've just been running my water from the tap, throught he tube and into the drain.. Not very green

[3roomlab]

I was just making soup at the induction cooker
Id say an induction cooker + sealable pressure pot.
because the induction cooker has small thermal mass
so all the cooling is now on the pot
the heating profile of induction cookers are not bad in simulation.
after cooking the pcb, take the pot and dip the whole thing in a sink of water
but this is so uncontrolled temp drop
but I do not know how to calculate the pressure of hot galden soup
lets hope the pot leave no after taste for the chicken stew.
ok no, this cannot be happening haha

[3roomlab]

A suitable frying pan should be obtainable for less than $100,  ( this is 2400W one, and was $89NZ )

I had a peek at some pictures of the temp profile

and I think you hit a spot with that 2400w
the slow ramp according to simulation needs around 250w, then the hard ramp needs around a 2000w rate. 
this is looking very interesting
but the graph rate look like 100C in 3s, while the simulation is 100C in 10s. I do not suppose there is a 6kW fryer? 
edit : after compensating for 100g of PCB, the wattage to ramp to peak 225C is now not 2000W but 2700W. the PCB was not properly accounted for in previous simulations.
a 100g PCB is estimated at around 40-50 J/K extra
with the 2400w fryer, and same conditions, the peak temp is around 210.