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

[mrpackethead]

that is a very aggressive curve,  a ramp of of around 6C/sec  from 160 would suffice.  30C/sec would be way too fast i thik

[trevwhite]

This video might be of use. Does not seem to be a very complicated setup.


Trev

[nisma]

If you need short process times, don't cool down to 100 degree (120 deg. + open lid = near immediatly 100 degr. )
Instead use a gate and lift. 
As reference, the process chamber is 30x30 cm of this oven, usable pcb size is 25x25cm .
 

[Kjelt]

If you need short process times, don't cool down to 100 degree (120 deg. + open lid = near immediatly 100 degr. )
Instead use a gate and lift. 
As reference, the process chamber is 30x30 cm of this oven, usable pcb size is 25x25cm .

Yes that is how the pro companies do it, the three temp sensors in the picture are solely for the heating control of the Galden, the vapor should stay above level 1 and around level2, it should not reach level 3 (overtemp).
On the carrier, best on the pcbs there are thermocouples for the reflow temperature control which is a seperate control loop.

[nisma]

No, the vapour need to reach level3, as otherwise the pcb is not at temperature, ie it heat up. 

[Kjelt]

That is a different machine I saw then.
The one I saw regualtes the temperature of the Galden so the vapor at level2 is about 230.
The temperature at level 3 is much lower so the pcb can be lowered conform the reflow profile (60 seconds or more soaking at around 160).
So where will the pcb be placed in the soaking stage in your example?
It has to be below the gate but there the te perature is not allowed to be 230C.
So yes there will be some vapor gases there but not the thick 230C vapor for the final reflow stage.

[nisma]

You statement can be true. In reality one can select sensor 1 (for glue hardening or pcb baking), sensor 2, sensor 3 or sensor 4 (external) as heating termination and start of cooling.
The lift lower the pcb to the reflow height. The reflow height is between sensor 1 and sensor 2, more near sensor 1 .
If the pcb have a certain height, sensor 3 or eventually sensor 4 is needed, otherwise sensor 2 can be used.


 

[mrpackethead]

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

So, i coud'nt help myself and i found a 'refurb' one of these for sale.    Its a breville BF560.   Stuck about 100ml of galden in teh bottom and heated it up.. ( with the lid on ).. I stuck a thermocouple probe through the lid hole and put some fire putty around it to seal it..     

Its got plenty of capacity to heat the galden. It boilded and created a vapour cloud..  I suspect that it willa ctually need more like 300mL    Some of the soft vapour did rise as high as the lid, but it condensates on teh glass, rolls down the lid, and back into the pan.  Its got a lip around the edge so it seals up well and any liquid drops back..    Without being absolutely certain it appears to run without looseing any galden.   I did this all with the frying pans own controller, but clearly thats not quite going to be whats needed to do the real job.

With it being a bit more shallow than your typical setup, leaving the lid on is going to be critical.      Its cool down is too slow and thats going to require some cooling.  I'm going to put about 3m of stainless steel 4mm tube in there and set it up for water cooling.   Possibly you might get away without this, but i'm not so happy with leaving my boards at elevated temp for exstended periods.

On the face of it, this certainly seems to have potential.   There are some saftey considerations,   Galden Vapour is very dangerous from a burns potential. You absolutley do not want to get in contact with it..  so, a bit of a lock out on the lid is going to be needed as well.

[Kean]

Its cool down is too slow and thats going to require some cooling.  I'm going to put about 3m of stainless steel 4mm tube in there and set it up for water cooling.   Possibly you might get away without this, but i'm not so happy with leaving my boards at elevated temp for exstended periods.

I would think you'd probably need to thermally bond a water cooling "jacket" to the outside of the pan.  Having something that sits inside would take up precious space, and if not bonded it wouldn't be very effective overcoming the thermal mass of the metal pan.

[3roomlab]

how do the factories get rid of the galden stuck on the pcb removed from the pot?

[Kjelt]

how do the factories get rid of the galden stuck on the pcb removed from the pot?

Probably the cooling fans blow it off 

[mrpackethead]

Its cool down is too slow and thats going to require some cooling.  I'm going to put about 3m of stainless steel 4mm tube in there and set it up for water cooling.   Possibly you might get away without this, but i'm not so happy with leaving my boards at elevated temp for exstended periods.

I would think you'd probably need to thermally bond a water cooling "jacket" to the outside of the pan.  Having something that sits inside would take up precious space, and if not bonded it wouldn't be very effective overcoming the thermal mass of the metal pan.

the tube is only 4mm high, and its not really an issue space wise.  Your board does sit on the bottom of the pan, you sit them on a frame that lifts it approx 15mm above the bottom.     My experience with using water cooling tube like this previously is that its very effective in getting the heat out of the galden quickly.   

[mrpackethead]

how do the factories get rid of the galden stuck on the pcb removed from the pot?

my practical experienec is that by the time the board has cooled down sufficently so you can pick it up, theres very little ( if any ) galden left on it.  I'm assuming that it probably evaporates off the board

[mrpackethead]

A quick test..   Electric frying pan at 100% power,  100mL of galden put in the pan.      It took about 115 seconds to get enough heat to create a vapour cloud about 60mm deep.     Too fast, but shows theres more than enough power to do the job.   By changing the power level from 'sear' to 'simmer' I was able to control the height of the cloud quite easily..    Obviously doing this by hand is not really a good plan, but a thermocouple at the right place, plus a small microcontroller can do this without hassle.

I did have a small amount of visisble vapour, get out of the pan, but this is very similar to the IMDES system and I am pretty confident that it is water that is being boiled off.  It only occurs at the start of the the heating.. The galden itself never gets anywhere near the edge.

I'll paste up a board and make a video later. I'm very confident that this will work and work well, with a bit of smart control.   As i have continously mentioned, MUCH care must be taken with Galden Vapour, it will burn you very badly.. If you are going to do this,  be very thoughtful about this.

I've now seen enough to know that this will work really well.,

[mrpackethead]

So, i thought i'd just try this out, and see how it goes. Found an old spare pcb and stuck some paste on it very quicky and very messily...    (* yes, i know, now i want to do it for real with a proper stencil printed board ).  (Its Henkel CG10 paste which is a very poor choice for hand application, it does not flow well out of a syringe, and it was cold

It reflowed nicely, with just 100mL of galden. 

these were only fesiblity checks to see if it is workable.   The next thing to do, is to put a control loop around the heater, with a thermocouple and control the heater.

 

[mrpackethead]

This is what happened with the fryer power at 100%.   I stopped heating at 390Seconds after i started.   There was 100ml of Galden in the tank.

The tip of the thermocouple was positioned so it was where the pcb would be.

[mrpackethead]

so,

(1) Its pretty clear that the ramp up is too fast, and it needs to be slowed down. This is done by controlling the amount of energy that goes in.

(2) There is a lot of energy left in the system once it reaches ~230C..  This is way too long for a sensible reflow and will need to be actively cooled.

[ChristopherN]

Has anyone tested using Teflon / Anti Stick coated pans? I have a very large board that I need to reflow and nothing to do it.

I did find this: https://shop.metro.de/Hendi-Partypfanne-239605-2810.html?c=185

It would be large enough and there is nothing too sensitive on the board so a slow ramp will not really hurt.

[mrpackethead]

I suspect that frying pan vapour phase is quite a new thing.  :-)   

I can't see any issue with using it. It shoud'tn get hot enough to come off. THe only thing i'd worry about is if the flux gets stuck on it.

[mrpackethead]

Clearly being able to control the power settings in this thing will be pretty crtical.   For some testing i'm going to use this DMX Controlled DImmer pack, its got some pretty big triacs, which will do the job nicely.

[ChristopherN]

Ok, I'll get one tonight and report how it goes. I have some temperature controllers laying around that can be controlled using RS485, so it should be easy enough to rig something together.

[mrpackethead]

I see that pan is only 6cm deep.  The one i've got is nearly 10cm deep and its only just deep enough.. THat might be a problme, as your galden might get up to the top very quickly.

[Kjelt]

In the old vapor phase topic I read that Galden also vaporates on room temperature.
They advise to store it in an airtight container after use.

[spongle]

Where did you end up sourcing your Galden?

[3roomlab]

I see that pan is only 6cm deep.  The one i've got is nearly 10cm deep and its only just deep enough.. THat might be a problme, as your galden might get up to the top very quickly.

you should totally try a soup pot, a deep 1