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How about hot steam for unsoldering (more effective than heat gun?)

Kabelsalat

Jul 5, 2011
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So today was a nice day, 10 degrees and a little windy. If it was a little warmer, the condition for de-soldering using heat gun would be perfect.

Ok, so this is about method for mass-disconnecting most or all components on a pcb board. Still testing out for finding best methods (today about preserving plastic sockets at the edge of pcb).

While standing with the heatgun in my hand working on a socked that simply refused to get off, I started to have a taught. Using a heat gun this way is less than ideal because it often isn't able to transfer heat fast enough, and when poor conditions it may take too long time for the solder to melt, causing the pcb to crack/smoke and the component itself accumulate more heat than it can withstand.

So I was thinking - what if, instead of using pure air flow, use super-heated steam? Steam (thus water) in comparison to air have much better capability to transfer heat. Of course, I don't have the tools nor the skills to create a boiler and pipe for releasing/spraying hot steam on a little area, at least in a safe matter.

Of course, safety must be the biggest concern of design. But if assuming that al safety problems are solved, you think such a method can be useful (i.e. more effective than heat gun) for mass-desoldering of components ?
Another concern I have is environment, because if using steam, then if working outdoor then the steam/water may drip into the ground causing some pollution. But, a heat gun will also provide some smoke going to the air from burning pcb board - so not sure what is worse. What do you think on this?


Anyway - compared to using solder iron, desoldering using heat gun have following advantages/disadvantages in my opinion:

Pros:
- Easy to mass-remove components from PCB boards.
- Very easy to remove components with many pins from pcb, such as IC's and connectors.
- Very easy to mass remove smd components of any form or size from pcb.
- Doesn't "eat" solder iron tips nor pose wear and tear on soldering equipment.

Cons:
- 10 degrees Celsius is the lower practical limit. If lower temperature, the heat loss on other side of PCB cause it to take much longer time for the heat to melt soldering on both sides. The consequence is often burnt pcb (and thus a lot of smoke), pcb being very soft, pcb bulging out causing heat transfer to practically stop - and of course this means the component supposed to remove gets overheated.
- Very dependent on the pcb ability to transfer heat from one side to another. Two similar pcb with same component may behave completely different. One pcb board may be "nice" and make it easy to pull the component out while the other completely deny heat to transfer causing the solder to not melting (implies overheat, lot of smoke and to give up because by then the component are probably dead).
- Due to excessive amount of smoke and gasses, this has to be done outdoor, and it have to be some wind to ventilate the fumes.
- Components composed mostly of plastic are very prone to start melting before the solder is fully melted. Typical for wire terminal blocks, other connectors and relays.
 
Last edited:

Delta Prime

Jul 29, 2020
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How about an environmental & or evacuation chamber.
Ultra-high vacuum ( UHV) characterised by pressures lower than about 1 × 10 −6 pascals (1.0 × 10 −8 mbar; 7.5 × 10 −9 Torr.Heat up the chamber to melt the solder, press a button & all the solder gets sucked out & maybe a few components.
 

Bluejets

Oct 5, 2014
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Anyway - compared to using solder iron, desoldering using heat gun have following advantages/disadvantages in my opinion:
Mmmm...so you routinely throw your tv, frig and washing machine in the bath to give 'em a quick clean as well..??
Suggest you line up for the crazy train.
 

kellys_eye

Jun 25, 2010
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Does the OP realise the energy cost perspective of using super-heated steam?
 

Kabelsalat

Jul 5, 2011
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Mmmm...so you routinely throw your tv, frig and washing machine in the bath to give 'em a quick clean as well..??
Suggest you line up for the crazy train.
Thanks for your "concern" about my psychical health, however I tend not to resorting to online forums to get evaluated. Also like many of the other "experts" on psychical health on various forums I cannot see how this comment can be of any help, for me nor for any others reading this.

Btw: On other forums (i.e Toms hardware) there is a pretty low threshold for users being temporarily banned on comments like this. Can I advocate for slightly more stricter rules (i.e obvious gas lighting)? Why I bring this up - because newcomers that for long time may only lurking around te forum but not posting may decide against posting, because not everyone can stand the uncertainly of being gas lighted because the they have in mind feels a little silly.


How about an environmental & or evacuation chamber.
Thanks for idea. However, I think there has to be manual labor involved because components having pins through the board tend to stuck until manually pulled off by a plier. For SMD-only boards this method may work.


Doubt that will heat the joint sufficiently to melt solder, and some of the steam will condense so you will end up with a wet board, likely not desirable.
True. Thanks for your reflection on this topic. Yes it will condense and wet board is certainly undesirable - unless already outdoor and the board is junk anyway.


Does the OP realise the energy cost perspective of using super-heated steam?
For heat gun I have. However, the wattage calculation for steam is harder because I don't have a model that gives a realistically amount (yet). A big tank is obviously a bad idea for a little project, like one board. A little tank is also not good because it need to cool down and being heated up again, which takes extra time.
 

poormystic

Jul 23, 2023
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I kinda like the idea of superheated steam, but I wouldn't try it.
Steam is too dangerous for casual handling.
 

Bluejets

Oct 5, 2014
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So I was thinking - what if, instead of using pure air flow, use super-heated steam?
Not practical one would think given the processes and the equipment needed to get to the required temperatures.
Again not practical given the costs involved with manufacture and certification of the steam generator device and associated equipment.

.............so, back to the heat gun.
Someone REALLY needs to close that gate they left open.
 

Harald Kapp

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Nov 17, 2011
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What you're trying to accomplish is essentially the reverse of reflow soldering: heat the solder to become liquid, then remove the components.
Hot air can be used, but due to the low heat capacity of air, you'l need lots of hot air.
Hot air is used for repairing components that use ball grid arrays (BGA). The respective repait stations are very expensive, however.

The alternative would be vapor phase (de-)soldering. But this requires a closed chamber and some ingenious method to remove the components from their bed of molten solder...
 
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