Depopulated board in oil

Well I did a little experiment today, I tried to depopulate a ram stick in hot baby oil. I can’t be the only one to ever think of that but I haven’t seen it posted anywhere before so I tried it.

I figured all I needed was something that boils higher than the melting point of solder.

I’m sure there is a better oil, maybe olive or something but it’s reusable and the baby oil smells kinda good when hot. Just thinking outside the box as I’m finally getting ready to process @50 lbs of ram sticks and after the painstaking process of cutting off fingers I was looking for something cheap and effective.

I also tried dissolving bga chip in Ethylene glycol and a catalyst after reading a paper about it, I used sodium hydroxide but the paper was about TBD ? as a catalyst compared to other catalysts.

Anyway that didn’t work for me.

But the oil bath with a little agitation stripped chips but the solder will wick onto anywhere it can so if there are still fingers on the board the solder may flow there.

Just thought I’d post the info, commensurate flaming :mrgreen:

Williamjf77 said:

I used sodium hydroxide

Click to expand...

Careful, that will strip the gold if the concentration is too high.

Olive oil will start smoking around 350F. It will scorch around that or lightly higher giving a foul odor and taste. Have you considered a rotisserie type toaster over? I have always been curious if one of those would do that job. I have an oven here I just don't get much escrap these days to try it on.

Actually I saw one of those rotisserie ovens at a local pawn shop, I might pick it up tomorrow.

I was just experimenting, I think canola oil smokes @ 230c, that would be cheap.

I was envisioning a big turkey fryer pot with 50lbs of ram sticks on a charcoal fire.

I was thinking if I could heat chips in a solvent that boiled high enough to pyrolize and depopulate in one shot that would be a win. If pyrolysis temp is @350c, and the oil boils at@ 350c and there would be no oxygen because of the oil.

But I gave up after the smoke got too much.

Just a theory but seems logical right?

And any hydrocarbon off gas would dissolve in the hydrocarbon solvent.

I’m no chemist but I love the science.

I saw a video once of a machine depopulating boards. It was nothing more than a big rotating basket with a heating element and controller in the top part. As it rotated and the heat became enough the parts would drop through the mesh of the basket and was caught in a tray under the basket.

My rotisserie came from a yard sale for $10 and came with a toaster basket made of 1/2 and 1/2 inch mesh. I had thought about using it but I only have around a pound of memory left. I might check tomorrow and see how they fit.

Johnny5 said:

Williamjf77 said:

I used sodium hydroxide

Click to expand...

Careful, that will strip the gold if the concentration is too high.

Click to expand...

Not to my knowledge.

Göran

Williamjf77 said:

I was thinking if I could heat chips in a solvent that boiled high enough to pyrolize and depopulate in one shot that would be a win. If pyrolysis temp is @350c, and the oil boils at@ 350c and there would be no oxygen because of the oil.

But I gave up after the smoke got too much.

Just a theory but seems logical right?

Click to expand...

Pyrolize, breaking down and driving off any hydrocarbons to leave you with only carbon and inert substances... in a hydrocarbon solvent? Either you boil the solvent off or char it. Either way it's more effort than just pyrolyzing the chips. Only chips would have less thermal mass and less hydrocarbon gases to get rid off. I can't see any problem that an oil bath would solve here.

Göran

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.

Anything that temp is surely dangerous.

There has been shown liquid pyrolyzing systems in here before, but they have been based upon molten salts. Not quite that combustible, and depending on the salts used, they can maybe be tuned to certain specific gravities for flotation and so on. Maybe....

But as I see it, it will create a horrible mess of fibrous glass and components with carbonized trash in there as well. Then it will still need incineration after the initial pyrolysis, if your plan is to refine anything the sorting will be next to impossible.

Or maybe the glass can be used as part of the flux and the whole shabang melted to bars for electolysis or sale?
Anyways, the whole thing seems quite messy to me.

Edited for clarity

g_axelsson said:

Johnny5 said:

Williamjf77 said:

I used sodium hydroxide

Click to expand...

Careful, that will strip the gold if the concentration is too high.

Click to expand...

Not to my knowledge.

Göran

Click to expand...

I've stripped masking from several hundred boards (fully gold plated), and witnessed what "appears" to be gold dissolution, from a few dozen. This situation happened to every single board exposed to the concentrated solution, and the "appearance" of dissolution only happened to parts exposed to the solution. Any parts outside of the solution still appeared to have it's original gold playing under the masking. It's entirely possible that I'm wrong, however Jack Burns, Frank, and myself were all talking one night, and they too experienced the same phenomenon. Again, I may be wrong.

Johnny

Mostly I just wanted to depopulate, with something cheap quick and reusable without directly using flames on the board, then I figured I’d leave it in longer to see but the smoke point of oil was just as bad as flames. So for depopulating it worked ok. Not something I’ll probably try again but who knows. Vacuum pump oil would work but that would defeat the cheap part.

Lead free melts below 200c so I don’t think that temp is crazy to work with, I mean French fries fry hotter than that don’t they

Does anyone know what type oil is used in an oil heater? The type that heats the oil in a closed system.
While I am not one to heat oil much, it may take more heat than some other types.

With a small amount of memory the oil thing might work. If I was going to do a large batch the hot oil would spook me into looking else where. Especially if I would be doing batches that size more than once, I would look into something easily repeatable with a wider safety margin.

Here's the thing.

It's one thing putting RAM in hot oil. Yes it COULD work I accept that. We put a process up on here where someone does it and before you know what's happening some eejit has put a PC board or similar in the same system and had the capacitors explode. Covering the workplace and probably himself in both red hot oil and shredded Aluminium.

There's another word for that shredded Aluminium. Shrapnel. I don't think anyone needs telling what shrapnel does. This is a really dumb idea lads.

Good point on the electrolytic caps.
See now there is information out there of why someone should not do that.

On a side note does anybody know why my AP solution smells like dumpster juice? I only used it to strip pins and just put the fingers in it yesterday. Is there a certain metal that does that?

Johnny5 said:

g_axelsson said:

Johnny5 said:

Williamjf77 said:

I used sodium hydroxide

Click to expand...

Careful, that will strip the gold if the concentration is too high.

Click to expand...

Not to my knowledge.

Göran

Click to expand...

I've stripped masking from several hundred boards (fully gold plated), and witnessed what "appears" to be gold dissolution, from a few dozen. This situation happened to every single board exposed to the concentrated solution, and the "appearance" of dissolution only happened to parts exposed to the solution. Any parts outside of the solution still appeared to have it's original gold playing under the masking. It's entirely possible that I'm wrong, however Jack Burns, Frank, and myself were all talking one night, and they too experienced the same phenomenon. Again, I may be wrong.

Johnny

Click to expand...

Led and tin will dissolve in lye, that can plate out on some of the conductors thanks to different metals gives different potentials like a battery or cementing back. That's why you see one finger turning white next to a golden one. The gold is still there, just covered by tin.

Göran

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