Electronics > Projects, Designs, and Technical Stuff

Vapour phase Soldering

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MK:

--- Quote from: tautech on February 03, 2015, 08:24:32 am ---
--- Quote from: tautech on February 02, 2015, 07:35:13 pm ---For a hobbyist to buy and keep an Argon supply on hand will cost more than the litre of Galden.

--- End quote ---
Good to see that not everybody gets raped on industrial gas pricing like we do in NZ.
Bottle hireage ~$120/year
Re-fillable bottle purchase $500 up
2 m3 fill ~$80

Hence the reason behind my statement


--- Quote from: MK on February 02, 2015, 10:23:08 pm ---Air, density about 1.2 Kg m3, Argon about 1.6 Kg m3, galden ht230 has a molecular weight of about 1000, so ~26kg per m3
www.g-werner.at/de/downloads/solvay_solexis_galden.pdf

--- End quote ---
.

So what is an educated estimate of the m3 of vapour from 500ml of Galden?
Cause you can't see the stuff, how big might a suitable vessel need to be?

Or is this of little concern as it will be ALL temp controlled?

From the datasheet linked above:


--- Quote ---The process is extremely fast and efficient since the
heat transfer coefficient of vapor condensation is
about ten times (10x) faster than hot air and about
eight times (8x) faster than infra red heat.
--- End quote ---

Doesn't that fascinate you, it does me.

--- End quote ---

500 ml of galden at 230 centigrade will be about 33 litres or just a bit more, then you need to allow a reasonable volume on top to allow for the stirred layer not to lose any galden, as it costs quite a lot, down to your design skills to keep the galden where you need it.

MK
edited because I forgot to allow for the high specific gravity of galden.

jwm_:
Just throwing it out there, but perhaps brake fluid will work?

dot 4 has a 230C melting point, but is made of glycols so is likely flammable however dot 5 is silicone based and has a vapor point of 260C. I have no idea what else is in there though so I wouldn't want to breath the vapors, but perhaps another generally available silicone will work? Take appropriate precautions if you try this of course.

    John

mrpackethead:

As a starter for 10 points, I'm going to do my designed based on the following;

My tank size is going to be 400 x 300mm,  and i figure i want a vapour cloud of about 200mm thick.  Thats going to be 18l of vapour, which requires 272ml of fluid.    A heater 'well' will be big enough to have the heater and the fluid in.  I think i'll make that well big enough to house 500ml of fluid.     I want to have a pretty good "head room" for the cloud so, i think we'll build the sides up so they are 600mm tall.

I'll put thermocouples in

(a) the heating well
(b) a little above the liquid level for the well
(c) 100mm above the well.  This is where the board will sit, when it is lowered into the tank.
(d) 200mm above the well. This should represent where the vapour should 'reach'.   

Cooling system to be designed yet


jeremy:
Hello everyone,

It seems everyone has gone quiet on this front. I just wanted to let anyone interested know that I am indeed crazy enough to keep trying with this.

The UPS guy showed up today with a neat 7kg package (please don't ask how much this cost :'( ):




Note the warning about 300C, this stuff decomposes into hydrofluoric acid so great caution is needed with the heating.

I am having a container fabricated as we speak out of ASTM302 stainless steel, and the ASTM440 6.35mm stainless steel ball bearings for the induction heater are on the way. Unfortunately I had to get it made at a metal shop, as I do not have a TIG welder nor the skills to TIG weld. And the price of a good TIG welder pales in comparison to the price of galden.

I went stainless because I don't want to have to deal with oxidation at all. It was a little more expensive, but I am considering this an investment in my own learning, and I hope in the open source community. I've gained a lot from open source, and if this turns out ok then I will document the project and make it available online as my way of giving back.

I also have some 3mil/3mil breakout boards coming with a 0.5mm pitch BGA on them (atmega48) for testing. But they were slowed up by Chinese new year, so I don't have them yet.

As a very strange sidenote, the inside of the package smells like mint (including the paper documentation). I have no idea why.

In the meantime, I've been brainstorming some ideas for computer vision software for machine-assisted placement of fine-pitch BGAs. But now that the galden has arrived, I'm planning on doing some characterisation experiments with it, particularly with respect to the evaporation rate. I can't guarantee I'll be able to do anything else as my real work is about to crank up, but if anyone has any good ideas for some tests please let me know. Keep in mind that I'm an EE, not a chemist ;)

My bank account hurts, but it's for science.  ^-^

IconicPCB:
Nice one Jeremy.

I also have a container on the way and need to purchase some of the chemistry.

I dropped anote to solway enquiring where in this part  of the world I could get the fluid. So far silence.

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