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Topic: The solder on a board I'm trying to harvest just won't melt... (Read 4137 times) previous topic - next topic

wyager

In an abandoned server room, I found in the remains of what I believe to have been an industrial UPS a board covered in LED bargraphs (among other things).

The bargraph board is wired very strangely, and I absolutely cannot figure out the proprietary connector it uses. The markings on the board don't seem to match any datasheets either, so I've decided just to remove all of the LEDs and drivers. The problem is, they seem to have used steel for solder. Even turned up to maximum heat, my iron doesn't actually melt the solder, it just makes a tip-shaped impression (while it melts the solder I use instantly). There also seems to be some kind of transparent glaze covering the board, which could be related. Does anyone have any advice for getting the LED bargraphs out?


mowcius

I would suggest trying to add some of your solder as you do it - sometimes this helps it melt the old stuff.

Could you borrow a hot air gun? hot plate?

What power is your iron?

RuggedCircuits

The transparent glaze could be "conformal coating". It's not cheap, but you can get conformal coating remover:

http://www.newark.com/techspray/2510-p/conformal-coating-remover-1pint/dp/69K7673

You may want to play around with household solvents too in case you're adventurous: good old isopropyl alcohol, nail polish remover, etc.

If you have a bigger tip for your iron, try switching to that. Often it's not the temperature that fails to melt/solder joints it's the lack of thermal mass to transfer heat to the joint (i.e., tip size).

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wyager



Dremel?


This is what I was thinking as a last-resort option...


I would suggest trying to add some of your solder as you do it - sometimes this helps it melt the old stuff.

Could you borrow a hot air gun? hot plate?

What power is your iron?



OK, I can try that.

I was considering just buying one from harbor freight for SMT soldering, but if my iron can't even do it...

40 watts.


The transparent glaze could be "conformal coating". It's not cheap, but you can get conformal coating remover:

http://www.newark.com/techspray/2510-p/conformal-coating-remover-1pint/dp/69K7673

You may want to play around with household solvents too in case you're adventurous: good old isopropyl alcohol, nail polish remover, etc.

If you have a bigger tip for your iron, try switching to that. Often it's not the temperature that fails to melt/solder joints it's the lack of thermal mass to transfer heat to the joint (i.e., tip size).



Jeez, that is expensive... I tried acetone, and I don't think it did anything. I'll try using the bigger tip, but my precision tip has never been insufficient for simple thru-hole stuff before...

weirdo557

when conformal coating gets in the way of me i usually just scrape it off with a file and then put the soldering iron on the exposed area.

Senso


cr0sh




Dremel?


This is what I was thinking as a last-resort option...


I would suggest trying to add some of your solder as you do it - sometimes this helps it melt the old stuff.

Could you borrow a hot air gun? hot plate?

What power is your iron?



OK, I can try that.

I was considering just buying one from harbor freight for SMT soldering, but if my iron can't even do it...

40 watts.


The transparent glaze could be "conformal coating". It's not cheap, but you can get conformal coating remover:

http://www.newark.com/techspray/2510-p/conformal-coating-remover-1pint/dp/69K7673

You may want to play around with household solvents too in case you're adventurous: good old isopropyl alcohol, nail polish remover, etc.

If you have a bigger tip for your iron, try switching to that. Often it's not the temperature that fails to melt/solder joints it's the lack of thermal mass to transfer heat to the joint (i.e., tip size).



Jeez, that is expensive... I tried acetone, and I don't think it did anything. I'll try using the bigger tip, but my precision tip has never been insufficient for simple thru-hole stuff before...


It might be (without seeing pics of what you are working on, of course) because it came from a UPS or similar, that it has high-current traces or such with a lot of copper, and if there is enough solder - simply acting as a large heatsink; the heat gets drawn away quicker than it can melt the mass of solder. The conformal coating is likely not making things easier.

I would go for the heat-gun and/or hotplate (or maybe toaster oven) approach - whatever you do, though, only use an oven or hotplate that won't -ever- be used for food again (lead and food don't mix - well, they do if you want lead poisoning). You need something that can deliver a lot of heat over a large area; much more than a pinpoint of 40 watts.

You will want to do this heating outdoors in a well ventilated area - a fan to blow any fumes away from you would be helpful. I wouldn't worry about the conformal coating in this process, as it will likely melt/burn/vaporize under the heat (but if you want to try to remove it, you can try a variety of solvents; you may have to soak the board overnight - let it dry completely before heating). You will also want to wear goggles, perhaps a face shield, gloves, long sleeves, long pants, and shoes. Why will become apparent shortly.

The simplest thing to do would be to mount the board parts side down between a couple of metal bars or such (something high-temp heat proof), then put a box or a pan or something underneath the parts side (to catch the parts), then use the heatgun (or heat the board up in the hotplate or oven) until the solder is melted, then use a board, or a rubber mallet to tap the board/parts to force them out and into the pan. You'll want to secure the board well so it doesn't bounce and fall, but so that it it still "springy" (maybe use some c-clamps at the corners) when struck. Because the solder will be molten, it will probably splatter around, hence all the safety gear I suggested wearing.
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AltairLabs

Being completely serious here, use a propane torch.

Go outside with a cardboard box lined with a cotton (not synthetic, no ESD) towel.  Fire up the torch and start roasting the backside of the board as hot and fast as you can, the coating and board will blacken and char in just a few seconds, the solder will be well molten. Instantly WHACK the board on the rim of the box, most of the loosened parts will fly into the towel to cool.  If you heated the board aggressively enough only the leads will be hot anyway, the heat does not have time to reach the component bodies before the WHACK.

Dont try to reheat to get parts that fail to come loose on first whack, toss them, like popcorn that fails to pop.  With practice a good cook can harvest 90 to 98% of the parts with 2% of the effort.  Ive not experienced any harm to harvested components aside from having to pick off a few solder splashes.

cr0sh


Being completely serious here, use a propane torch.

Go outside with a cardboard box lined with a cotton (not synthetic, no ESD) towel.  Fire up the torch and start roasting the backside of the board as hot and fast as you can, the coating and board will blacken and char in just a few seconds, the solder will be well molten. Instantly WHACK the board on the rim of the box, most of the loosened parts will fly into the towel to cool.  If you heated the board aggressively enough only the leads will be hot anyway, the heat does not have time to reach the component bodies before the WHACK.

Dont try to reheat to get parts that fail to come loose on first whack, toss them, like popcorn that fails to pop.  With practice a good cook can harvest 90 to 98% of the parts with 2% of the effort.  Ive not experienced any harm to harvested components aside from having to pick off a few solder splashes.


I would recommend to anyone following the above to do this while wearing protective clothing, face mask, goggles, possible a respirator too - that PCB is going to throw off some hella fumes and such, and you better pray that none of your neighbors call the EPA (or whatever your country's environmental protection agency is called) - as I am sure you would be fined for pollution reasons...

There's a reason why so much electronics gets dumped in china and other places - it so they can do harvesting like this (mostly for metals, though) without any oversight as to the environmental and health damages they are causing...ugh.
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

And this is assuming you won't melt the plastic on those bargraphs and LEDs...

I do agree with cr0sh... be careful with how you do it. I'd give it a try with the file and a heavy duty soldering iron. The larger tip does make a difference.
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AltairLabs

Assuming you guys dont consider adequate safety equipment to be a coupla bottles of Samuel Adams.

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