Homebrew vapour phase oven?

[mikeselectricstuff]

I was wondering how hard it would be to make a homebrew vapour phase oven, to avoid all the problems with very cheap conventional batch ovens, in particular uniformity.
I've seen a reference to a pasta cooker VP setup, but the image link is dead now. A deep-fat fryer would appear to be a reasonable candidate in terms of size and temperature.

I can't immediately find much info on the general practicalities of commercial VP setups, in particular :

How do they control the level of the vapour blanket? Does this effectively set itself from the applied heating power and losses from the walls, or is there an active cooling zone, or some sort of closed loop between vapour level and heat input ?

How much fluid gets left on the PCB afterwards - does it re-evaporate once the PCB reaches the vapour temp?

Is there any appreciable evaporation loss at room temperature?

How is the rate of temperature rise typically controlled? Is it as simple as controlling the descent rate of the PCB into the vapour, or is there some additional pre-heating hardware?

And the real important question - roughly how much does VP fluid cost in the smallest available container, and how small is that container..?

[mikeselectricstuff]

Just had some prices on fluid - Galden LS-230 about GBP500 for 5Kg, LS-240 GBP600
Density is 1.82 so that's about 2.7 litres.

This small machine needs a minimum of 2kg. I've seen a figure for fluid running costs of GB0.01 per minute.

[ktownsend]

Do you have an estimate on price for that oven? Just curious.

[Alphatronique]

Hi

first it extremely dangerous since galden/fluorinert vapor was invisible and at 230 deg !!!
also that stuff have bad tendency to degrade into toxic fume
and the least if you not preheat the board you will make extreme thermal shock .

if you still read and interested this was how i process

my first prototype was build into a household fryer ,i put 2 set of thermocouple
spaced of 1" at the lever that i what the blanked of vapor (keep 6" safety from top)
whit controller put heater on when lower thermocouple was <set point and stop when second thermocouple > set point
so now problem come from that fryer cavity was aluminium so it need water colding tube around tub for avoid vapor escape

second prototype was a Stainless pan whit bottom painted whit black oven paint whit fitted 2KW of infrared heater under the pan
so paint absorb heat and it make good heat spread over big surface and since Stainless was pour heat conductor it avoid fume escape problem
but it definitively stop using it since fume problem was never resolved ,if you put fan for absorb fume you disturn the 230 deg invisible fume
so operator become really exposed ,all knot how much stream may burn and galden was more that twice that temp and totaly ivisible .....
and not to forget the price that was 70$ for 100ml so you have ~200$ of galden in the tub and you louse small part each time you solder a pcb
yes condensed vapor remain into pcb

as of result in my system in have soldered lot of CCD camera sensor in 0.5mm BGA whit > 85% yield

p.s. English was not my native language sorry for million of typo

Best regard
Marc L.
Alphatronique inc.

[mikeselectricstuff]

I think the cost of the fluid pretty much kills it as a cheap/simple solution, unless someone can come up wih a cheap homebrew fluid recipe...!