Depopulated board in oil

[Shark]

I went and cleaned up my rotisserie oven and heated it up. The downside is it has no way to control the heat or turning speed. It will reach 500F inside pretty quick the stabilizes around that number and the thing has very little insulation, if any, in it. The basket would need some tweaking to stop the boards from sliding out the ends. Any idea what an optimal temperature would be if it was used for memory only?

 

[Williamjf77]

I think 450f should melt the solder, most lead free melts below that and leaded even lower

 

[Shark]

Why not indirect heated sand bath. A large electric fry pan should work.

May even be possible to recover the solder once the sand is saturated.

I would try very course sand then sift out the contaminants once saturated. The solder and the small SMD devices should be there.

Once the sand is super-saturated it could be smelted to clean up the balance.

Have not tried it but I would think someone on the forum would have some experience.

Also I would advise proper ventilation, gloves and a respirator when doing this. A shield face shield would be a good idea as well.

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Edited for spelling

Several years ago I used that method to strip small boards. Like anything we do, it takes some work to get it just right, but does work. Then as Jon mentioned, and I had forgot, those capacitors are best removed first if doing larger boards. I have dodged one or two of those capacitors and is one of the reasons I went back to doing manually. There is a lot about board stripping I just do not miss..

 

[Williamjf77]

I have read about sand bath but am trying to avoid manually handling stick by stick. I’m sure I’d be half done by now just doing a proven process instead of trying new thing. I like the trammel style depopulated like the rotisserie. I do have a lathe maybe I can rig up a temp solution.

 

[butcher]

Oil? I would not even consider as an option to depopulate circuit boards.

I have used several methods to remove components from circuit boards.
Rotary tools to cut or an air chisel to shear.

Hot air gun will melt solder, and a bang of the edge of the board against the table to knock the components free.
Sand bath to desolder and knock on the table.
Using a desoldering and suction station.

I would like to try something that would be similar to a clothes dryer where you could control the hot airflow through the drum to melt solder, yet not harm the electronic components...

 

[rickzeien]

I would like to try something that would be similar to a clothes dryer where you could control the hot airflow through the drum to melt solder, yet not harm the electronic components...[/quote]








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[rickzeien]

Tried to edit quote but my comment didn't come over.

I really like this idea.

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[rickbb]

Depopulating boards on anything other than large industrial scale with expensive equipment is a pain.

I've not found anything faster than just holding a single board at a time with pliers on a hot plate and scraping off the components with a wide blade putty knife.

If you get a rhythm going you can scrap off the bits without any smoke at all. But you will still need ventilation, stuff stinks and is not healthy to breathe.

A hot oven with a rotating wire basket that would hold poundage of all kinds of boards sounds like a winner.

 

[Shark]

At 5 minutes this was the results.






A very short video at the 10 minute mark. There was no smoke, and very little odor, and actually smelled like solder more than anything. I don't like the factory basket, and actually think a more rounded one or even a square shape would work better. The banging as the sticks dropped did knock off many components.

[youtube]https://youtu.be/9SZUX9IVvQ0[/youtube]

 

[rickzeien]

Looks great Shark. Did it completely depopulate and remove the the solder?

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[Shark]

No, it left some on the boards and some on the chips. It looks like most of it remained with the boards, but only in a few spots. Both are cleaner than using a sand bath or a butane torch. The sliding action and the boards bumping together seem to remove some solder as there is solder balls in the bottom pan. I only ran these for 15 minutes and it took that long for glass type chips to start coming loose.The old chips with legs came loose first (at about 5 minutes), the newer square epoxy type and the mlcc's came off next at about 9 minutes. The oven I am using is a Sunbeam model RE12-12. The only heating element is high on the back side and I think that is plus. It keeps some heat away from the components after they fall off. If I can I want to try a longer run tomorrow, it is getting to dark now. I have an idea on how to get the chips to leave the oven I want to look at closer tomorrow as well.

 

[snoman701]

Does a 300 degree C hot oil bath seem somewhat dangerous to anyone else? It's fraught with hazards.

For one, the reaction of many components to that level of temperature is best described as explosive.

You mean since the auto ignition temp of mineral oil is right at the temp he heated it too? Yes. Just a tad dangerous.




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[Shark]

This this took 3 hours to run in my small oven. It don't look like much but the chips are in a 1.5l dish. It did leave enough time in between changing out the boards to decant my stock pot into the iron bucket. Refill the stock pot and set up a new, quieter way to circulate the solution. I have no memory left to play with, and it will be a while before I expect to have very much again, but I do have other ideas to try with this thing yet.

 

[Williamjf77]

This this took 3 hours to run in my small oven. It don't look like much but the chips are in a 1.5l dish. It did leave enough time in between changing out the boards to decant my stock pot into the iron bucket. Refill the stock pot and set up a new, quieter way to circulate the solution. I have no memory left to play with, and it will be a while before I expect to have very much again, but I do have other ideas to try with this thing yet.

1105191407.jpg

How about the new way to circulate the stock pot? Care to elaborate.

 

[Shark]

Give me a few days to see how it is working. As of now, it seems to be good.

 

[Williamjf77]

Nice, I like the rotisserie, especially the rectangular basket, the shape gives an impact to knock the chips off as it turns

 

[Shark]

For me the oven is like a proof of concept. It should be easily scalable to suit ones needs. I like that idea of using a cloths dryer, if one has the material to make it worth while. Done right, the chips will drop and exit the area that is being heated. What I would like now is to figure out how to get the cleaned boards to leave the drum and deposit in another area separate from the chips.

 

[butcher]

Not actually a clothes dryer.

https://www.google.com/search?sxsrf=ACYBGNSZA2joWFgAB8jcTRqoEFvYw_EDBg%3A1573011303358&source=hp&ei=Zz_CXbKHE5bD0PEPm8SDiAI&q=rotary+drum+roaster&oq=rotary+drum+roaster&gs_l=psy-ab.3..0i22i30l3.10734.23108..26103...0.0..0.175.2153.5j14....2..0....1..gws-wiz.......0j35i39j0i131.vR-PMy_M1mw&ved=0ahUKEwjy1tjf09TlAhWWITQIHRviACEQ4dUDCAg&uact=5



https://www.google.com/search?q=rotary+drum++ore+roasting&sxsrf=ACYBGNQCqNvwOo33DsMHXQPlDKLl4CwQBw:1573011423771&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiIt5CZ1NTlAhW6FTQIHTsYDlkQ_AUIEigB&biw=1280&bih=881

 

[kernels]

DIY version of the ram depopulator -> https://www.youtube.com/watch?v=wzWB66dLBok

 

[anachronism]

What you are really looking for is a reflow oven. You can pick them up second hand extremely cheap. Then all the work is done for you.

The search term is "reflow oven."