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Vapour phase Soldering
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Zucca:
Sorry to jumping in without having read all those previous pages in details.
Looks a cool project, I´m wondering if it would be possible to get a cheap liquid and change the boiling point by changing the (vapor) pressure in the chamber:

Form Wiki:


http://en.wikipedia.org/wiki/Vapor_pressure

Take for example mineral oil:

http://www.sciencelab.com/msds.php?msdsId=9927364


--- Quote ---Boiling Point:310°C (590°F)
Vapor Pressure:<0.1 kPa (@ 20°C)
--- End quote ---

so if we create a negative pressure in the chamber (below 1 bar absolute) then it should be possible to get the 230°C boiling point or whatever you want. By then rising the pressure to the atmosferic one the vapor will turn into liquid and ready to take the final product out.

Surely there is a big elephant I am overlooking...

PS: OK, I got it. The solder melting point depend also on ambient pressure... another idea in the garbage can?
PS2: Anyone knows the solder melting point graph temperature vs pressure? I couldn´t find nothing on the www.
Kjelt:

--- Quote from: zucca on January 30, 2015, 09:55:57 am ---Looks a cool project, I´m wondering if it would be possible to get a cheap liquid and change the boiling point by changing the (vapor) pressure in the chamber:
--- End quote ---
You do not need to change the boiling point of the liquid, you need to have the temperature at 230oC for the solderpaste to melt  :palm:
If I vacuum soup or water  in a bag in my vacuummachine for instance it starts boiling at room temperature, but if there was an egg inside the soup it would not get hard boiled not even after an hour.
So you approach this the wrong way around I am afraid.
plazma:

--- Quote from: Kjelt on January 30, 2015, 11:14:13 am ---
--- Quote from: zucca on January 30, 2015, 09:55:57 am ---Looks a cool project, I´m wondering if it would be possible to get a cheap liquid and change the boiling point by changing the (vapor) pressure in the chamber:
--- End quote ---
You do not need to change the boiling point of the liquid, you need to have the temperature at 230oC for the solderpaste to melt  :palm:
If I vacuum soup or water  in a bag in my vacuummachine for instance it starts boiling at room temperature, but if there was an egg inside the soup it would not get hard boiled not even after an hour.
So you approach this the wrong way around I am afraid.

--- End quote ---

You could use a pressure pot and a liquid with lower than 230C boiling point. Increasing the pressure increases the boiling point.

Zucca:

--- Quote from: Kjelt on January 30, 2015, 11:14:13 am ---If I vacuum soup or water  in a bag in my vacuummachine for instance it starts boiling at room temperature, but if there was an egg inside the soup it would not get hard boiled not even after an hour.
So you approach this the wrong way around I am afraid.

--- End quote ---
Uh? If the boiling point if bigger than 230 C (mineral oil) than you need to lower the pressure.
I am sure if you read again my post you will understand. If you have any questions I am glad to help
gxti:
You'd have to find something chemically inert, because evaporating flammable liquids is a great way to get an explosion. But realistically I think all the added complications of containing a lower (or higher) pressure make it a far worse alternative than just paying for the inert, non-toxic, ambient pressure stuff. The price will come down the more popular it gets, and with a suitable apparatus you won't need much of it nor will you lose any during operation.
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