Deep depopulating - How do YOU do it?

[AndyWilliams]

Until today, I've been depopulating boards with a heat gun. They are cheap and easily available from places like Harbor Freight and Northern tool. Today, I bought a 7.5 inch square metal cake pan from Walmart ($0.92) and filled it a little over half way with play sand. Put it on the hot plate and turned it on. In 10 to 20 seconds,the boards get hot enough so that you can either tap them on a solid surface and the parts fall right off, or the components can be scraped off by just running a pocket knife over them. I couldn't believe how easy and fast this was. Saw it first right here on the forum, and as usual, you guys (and gals) are right on target. If you have the heat up too high, you can damage the circuit board. Conversely, if the heat is too low, it takes a lot longer before the parts are ready to fall off.

Curious, what temps does your hotplate reach? And what kind is it?

Yes, Inquiring minds want to know! I have been playing with this over the winter. But the biggest idea in my head is geo's setup, and quite frankly, I don't think I'm that handy!

 

[bswartzwelder]

I have no way of checking the temperature of my el cheapo hotplate. If left in the sand mixe for more than about 30 seconds, the boards themselves will start to turn a dark brown like they've been burned with a torch. By the way, it's a single burner unit from Walmart and I can attest it does a truly fine job for about $20.00.

 

[MEANIE]

Gold4mike check this out .
http://www.ebay.com/itm/SPEEDY-3-Air-Vise-Foot-Pedal-Control-/190789595506#vi-content

 

[bswartzwelder]

I forgot to mention, but in my last batch of AP, I intermixed some circuit boards which never had components installed and a lot of the flexible connector strips like in the second picture at the beginning of this thread. I poured the AP into another bucket through a super large filter and started examining what was left in the bucket. The bucket had been sitting in my back yard bubbling away for over 2 weeks. Anyhow, many of the circuit boards still had some traces of gold left on them. I set the nozzle on my hose to the shower setting and picked up a circuit board. Holding it over the bucket, I gently turned on the water. Almost no pressure was used and the gold washed into the bucket. A little rubbing with my fingers also produced pretty much the same results, except I had to hose the gold off my fingers and into the bucket. It also worked quite well with thos pesky flexible strips. Some of the strips had adhesive on them which turned into a funky stuff resembling gauze. It is VERY time consuming to do it this way, but the alternative would be to not do it and lose the gold. I can honestly say I have never seen so much gold in a filter in my life. Once I have finished the bucket, I'll let you know the weight of the foils collected.

 

[grahmdiam]

Hello, newbie here. I've been thinking about this and could either liquid oxygen or liquid nitrogen be used to freeze the plastic rock solid and then use brute force to smash and shatter the plastic. I don't know if it is feasible or even the logistics of acquiring the stuff, or the expense. Any thoughts?

 

[steyr223]

From an early age i taught my pitbull
A. J. To strip the ends of most connectors down to the pins ,she even
Likes to do the metal ones (serial,parallel) but i only let her do the plastic ones

A.j. left alone or at least to herself in a room with over 10lb of ide ends and a little motivating talk/play will strip all the plastic in less then 45 minutes and i dont even have to clean up the plastic except when i pick up the back yard :mrgreen:

I wish i had pics as A.j. is no longer with me and i dont have a house

Someday i will tell you what another pitbull i had use to do his name was copper :lol:

Steyr223rob

 

[Auggie]

I once took all the mylar ribbon cables from which I'd already cut out the gold bits (like the ones shown in the second photo at the beginning) and stuffed them all into a largish Dutch oven an covered it with the lid. I then put that in my firepit surrounded by lots of fuel (wood) all around and on top, covering the oven, then set it all aflame. I kept that fire going good and hot for about half an hour. Finally, I lifted the lid to take a peek at what was going on inside the Dutch oven and a brilliant blue and green flame erupted from the pot. The mylar had mostly burned away and the remaining gasses that came off the low/no-oxygen burn burned away once exposed to flame. I put the cover back on and waited another 15 minutes and lifted the lid to get more brilliant blue/green flames, and what was left was a dirty blob of fine copper wires. I plan to melt that down into a copper ingot.

 

[steyr223]

Question . If u did that on a larger scale
Like say filled the dutch oven up
Would you not get a.back draft when you lifted the lid
Maybe theres another name.,when i was incinerating the way holkes explains(and i understand its not recommended) i llifted the lid and was engulfed in a quick flash of fire.

Could be dangerous to the unprepared

Steyr223. Rob

 

[chlaurite]

I have no way of checking the temperature of my el cheapo hotplate.

Water boils at 100°C
Tin melts at 232°C
Bismuth melts at 272°C
Lead melts at 327°C
Zinc melts at 420°C
Sulfur boils at 445°C
Aluminum melts at 660°C
Zinc boils at 907°C

Unfortunately we have something of a big gap between 445 and 660, but I'd dare to estimate a typical hotplate pushes somewhere between melting lead and zinc with no other load on it. If you take basic steps to insulate it a tad (surround it with bricks, and it doesn't self destruct at that temperature), you might get all the way up to melting aluminum.

 

[butcher]

I have measured my hotplate on high at around 500 degrees Fahrenheit, which is about 260 degrees Celsius, this is the burner itself, then you have heat loss of the pot and material in the pot, acting as a big heat sink and the surrounding air sucking up heat.

My hotplate was made for cooking food, not for melting metals.

I run hotplates almost all the time 24 Hrs 7days a week sometimes months at a time, I have found they will run longer, or the hot plate will last longer without failure of the burner element, if they are not run on high for long periods of time.

 

[meatheadmerlin]

i say take a large metal coffee can or small metal trash can, throw them all in. Take a large slug hammer, you know the ones they use for breaking up rock or concrete and bash them up. that should break up all that plastic to the point were they will come out on there own, and then pull the loose ones out of the little bits of plastic left.

I've used this method with home and appliance electrical connectors, like switches and sockets, to get the brass out of them. I've found it very effective, but that plastic (bakelite, I believe) is usually very fragile compared to the kinds of plastics used in computers and electronics, which I've found tend to deform when smashed, more often than breaking.

As for ribbon cables, it's still a lot of manual labor, but this is one of the better methods I've seen for hand-pulling the pins.
http://www.youtube.com/watch?v=U2zWr0UPwrw
This youtube poster has many videos on mechanical separation.

He also has this video on RS232 connectors.
http://www.youtube.com/watch?v=9CVdPJsXbnE
This basic idea works for most PC connectors and plug ends with pins, I've found they have similar construction. I use an old pair of garden pruning clippers to cut the soft plastic away from cable-end connectors to get at the assemblies inside. That plastic is the same type of PVC as typical wire insulation on most of the cables I've found. They usually peel off pretty easy once you cut into them enough to find the assembly inside. Of course, once inside, you sometimes encounter a thick soldered shield (VGA plugs especially) that I am still puzzling over a cheap and easy way to deal with.

Anyway you slice it, mechanical or chemical, it's a lot of work to fill your idle time.

 

[Geo]

Rob, almost all material on earth has whats called a "flash point". thats the point where a material is so hot that when its exposed to oxygen, it will oxidize sometimes violently. the more volatile a substance is, the lower the flash point is. the organics in printed circuit boards are very volatile when released by heating. this means that if you heat pcb's in an enclosed space without oxygen and then suddenly expose them by opening the door, it could spontaneously combust without a spark and explode.

 

[chlaurite]

This youtube poster has many videos on mechanical separation.

Wow, I have a new favorite YouTube channel... This guy rocks!

Thanks!

/ Though the casual way he handles a CRT yoke... I have to suspect he's personally experienced the joys of 30KV more than a few times. :roll:

 

[Shaul]

Here's how I do it. I use a small electronics-grade diagonal cutter. For ribbon cable connectors, first cut or pull off the ends. Then insert the blades on the two sides of the connector (near the end) and simply pry the connector apart. You may have to do this once or twice depending on how many times the cable is looped back on itself. Oftentimes the cable will come off the pins with a number of the pins still attached, which can then easily be pulled off by hand. The beauty of using a small diagonal cutter is that it's small enough to get in between the rows of pins on a connector and pull them out 4 or 5 at a time. Just use enough pressure to grasp the pins without cutting them off. For RS232 connectors, I use the same cutters, but there's a difference between the Male and Female connectors. With the Male connectors it's often possible to pull the pins straight out the back without having to disassemble the connector. Otherwise and with almost all Female connectors: using a small, thin flat-blade screwdriver or a strong thin spatula, pry the metal connector open, on both sides of the screw hole, insert the diagonal cutter and cut right through the rivet (of the screw hole). The two sides of the metal connector can then be pried open and the plastic insert removed. It is also possible using a regular-sized diagonal cutter to insert it between the screw hole and the connector body and cut there. Even if it's not cut all the way through but just weakened, the end can then be wiggled back and forth for a few seconds until it falls off and the connector pried open and the plastic easily pushed out with finger pressure. Again, simply pry apart the two plastic halves and the pins come out easily with no plastic flying everywhere. In the event that there is solder stuck to the ends of the pins and they don't separate easily from the connector, the diagonal cutter set along the edge of the pins can easily cut through the plastic, freeing the problematic pins. Over the years I've done many hundreds in this way. Once you get the hang of it, it goes quickly and easily enough.

 

[haveagojoe]

I have had reasonable results simply putting these plastic connectors into AP whole. The foils eventually get released and the acid doesn't seem to affect the plastic. I don't wait until all the base metals are dissolved, just until I see a good amount of foils when I give them a stir. I probably don't get every last bit but the yield on these is very low so I don't worry about that. It's certainly not worth burning them or smashing them up unless on a huge scale.

 

[haveagojoe]

Sorry, I should have been more specific, I'm talking about the ones from phones, not the larger ribbon connectors

 

[johnny309]

Rocket stove(https://www.pinterest.com.au/pin/307863324511898366/)...is great to heat you up in winter....so gather material to process... :idea: Put some dry wood first.