# Methods of depopulating PCB's



## badastro

Printed circuit boards contain a variety of items that contain values. In order to obtain those values, the first step is to remove them from the board. In addition, the some boards might even have gold plated traces eg. cell phone boards.

Of the common methods to depopulate the boards, they fall into three categories: mechanical, thermal, and chemical.

*Mechanical*

Method 1: Manual extraction
Manual extraction involves using hand tools to remove items of values.

Examples: Using a sharp blade to extract "flatpacks" by running the blade across the legs of the package as shown in lazersteve's tutorial video. Using hammers, pliers, levers, metal shears for fingers, or chisels to smash or pry out components are also methods.

Pro: Method 1 is easy to implement with minimal resources.
Con: This method is very labor intensive, has low productivity, and can put particulate matter into the air. A mask is recommended.


Method 2: Powered tool extraction
This method involves using power tools to aid in extraction of items.

Examples: Using an air chisel to buzz off parts. Using saws to cut off fingers.

Pro: Fast and relatively productive.
Con: Not everyone has the required tools. It can be very messy as parts fly everywhere. Hazardous dust is produced, a mask is required.


Method 3: Milling
This method involves using hammer mills, ball mills, or other mills to crush and grind boards to dust.

Pro: It is the most productive of mechanical methods. It can be configured to batch or continuous processes.
Con: It is a considerable investment. It is very noisy and very dirty.


*Thermal*

Method 4: Heat gun
A heat gun is used to melt the solder to allow components to fall off the boards.

Pro: This method is easy to implement and very selective for clean removals.
Con: Toxic fumes can be produced. Over heating of the boards is possible. This method has low productivity and uses a lot of electricity which costs money. Other components are likely to fall off, especially smaller surface mount components. It also takes significant time for the solder to heat up.


Method 5: Sand in a pan
This method was suggested by one of our members. It involves filling an electric pan with .25"-.5" of play sand and resting the boards on the sand. The heat melts the solder allowing the components to be picked off. 

Pro: This method is easy to implement and can have higher productivity than the heat gun. The solder will pool under the sand and can be recovered and processed for values.
Con: This method is still time consuming and produces hazardous fumes.

Method 6: Vibrating oven
This method involves placing board in an oven with some mechanism to vibrate the boards so the components can fall into a collection pan.

Example 1: Place boards vertically in an old oven outside the house. Have a pan under the boards. Give the boards a good shake when the solder has melted or rig up some mechanical shaker.

Example 2: Build a rotating heated cage where boards can be fed in one end and come out the other. The rotation knocks off components which fall down out of the cage into a collection pan.

Pro: High productivity 
Con: It requires an investment to implement. It also produces toxic fumes. Not all components can be shaken off. It requires a lot of energy.


Method 7: Forbidden
Pro: Highest productivity
Con: You could make yourself and others very sick and go to jail.


*Chemical*

Method 8: Acid peroxide
Remove ferrous materials and dip boards into an acid peroxide bath.

Pro: This method is easy to do in small scales. It produces less fumes than other methods.
Con: It takes a long time to process boards--low productivity. It generates a lot of waste solution, which may have to be processed for values. AP is indiscriminate in what it will dissolve and is thus inefficient for depopulating boards.


Method 9: Hot acid bath
Remove ferrous materials. Place boards in a bath of straight or diluted muriatic acid in a crock pot. Do not boil and keep it covered. The acid will attack all solder and leave gold and copper intact. The process should be over in less than an hour.

Pro: Method 9 is fast and efficient. It only dissolves the solder leaving behind components, a clean board, and dirty acid solution. Some people crock pot pins anyway... 
Con: It can produce acid fumes. Hot acid is dangerous. The spent acid is very toxic. It is difficult of an average person to scale up.


Method 10: Thermal depolymerization
This method involves taking whole boards (or loosely ground up boards) and converting the plastics into oil, gas, and other useful components.

Pro: Scaling is unlimited. This process does not produce unmanageable toxic gases. It is the most efficient and productive. It will accept all wastes, even sewage, and convert it to oil.
Con: This method is unavailable to the average person.

comments meow?


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## lazersteve

Astro,

Great post! 

It's nice to have everything spelled out in black and white for each method. I really like the pros and cons section for each. :wink: 

AP can be a selective depopulation tool if it is used in a shallow dish. I've actually used it to 'desolder' components from boards thru chemical means. It's not exactly the cleanest or fastest process, but it does work.


Steve


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## blueduck

badastro said:


> Method 3: Milling
> This method involves using hammer mills, ball mills, or other mills to crush and grind boards to dust.
> 
> Pro: It is the most productive of mechanical methods. It can be configured to batch or continuous processes.
> Con: It is a considerable investment. It is very noisy and very dirty.



So instead of purchasing a ball mill, build one from an old tire and a couple of steel rolls, or steel rods on pillow block bearings a pulley and a couple of casters to keep the tire straight, use plywood to cover the center hole, cut a door in the thing and power the unit with an old electric motor of a horse or less.

www.acc.umu.se/~widmark/bigtumbler.pdf gives the details and such to make a unit that will handle about 50 pounds inside, and probably can be bilt for under $50 if you have a few parts laying around the laboratory/shop a far cry from the $800 or about for what the commercial units will set back the hobbyists such as the Lortone commercial units like the double 20pound drum http://www.lortone.com/commercial_tumblers

anyhow it is an option for some folks, especially for those of us who have limited funds to operate on.

William
Central Idaho


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## aflacglobal

http://www.rictec.com.sg/grinder/ecycler/


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## goldsilverpro

Badastro,

Excellent post!

blueduck,

The tire is a grinder that takes forever, It's not a crusher, with big balls that drop and crush the parts. I don't think it would work for most of our stuff. Interesting and cheap idea, though. Would probably work for a few certain items.

Ralph. 

Now you're talking! There's so much of this kind of equipment laying around rusty in yards (scrap, surplus, etc.) that can be bought for a song (much for near iron scrap value) and put back into service. Do they still print "Used Equipment", Ralph. Everything in that mag. is negoitable. 

Transportation, bearings (sometimes), electrical, paint, etc. is all you usually need. All equipment is out there used. It's out there. You just have to find it.


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## aflacglobal

Do they still print "Used Equipment", Ralph. 

I think they do. The market for items that scrap recyclers use ( Junk-scrap yard ) Is way over saturated. You can find items for nearly any application when it come to just tearing and shredding the shit out of it.
These can be drug out of a field and put back into service for pennies on the dollar.

I use to get some good leads and items from :arrow: :arrow: http://www.rossmach.com/


The lab sales ? I to have my eye on some items. The redstone arsenal , in huntsville, al. It's about 70 mile n of me. They sell some goooood army and space command materials from their inventory. They do space research and the home of the United States Army Aviation and Missile Command to ( they are one of two groups of people who push the button on your ass. ) . I have seen everthing on their base web site that is for sale. You would not believe what materials you can lay your hands on. It's scary.

Their are many science research companies in the area who support the base and the space command. When the deals are to be had, go to where their is a surplus of that item and you will find the lowest cost.


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## hyderconsulting

I did some work a while back on a method depopulating circuit boards by heating them gently on a large hot plate as a basis for removing components.

Take a hotplate and place on top a thin piece of steel plate to increase surface area. The plate can be anywhere from 8 inches to well over a foot in length and width but needs to be at least 1/4 inch in thickness. When you place a circuit board on the hotplate on low heat it will take up to 15 mins or longer to heat the solder up to allow components to be flipped or picked off from the board. This is of course slow so I had to figure out how to get the right amount of heat immediately to the entire surface area of the bottom of the circuit board without burning everything up. What actually slows the heating up of the bottom of the board is the component legs and solder sticking thru the board bottom which creates an air pocket between the circuit board and the hot plate surface. No instant heat. So what I did was put the circuit board in a vise or holding clamp and run a hand held grinder over the bottom to knock of the legs sticking thru. You have to wear a full face mask and gloves for tiny pieces of hot metal fly everywhere! I then took the board and run it for a minute or two on a belt driven sander to further flaten the botton of the board and get it smooth. Here gloves and a face mask are necessary to not breathe metal dust. When I put the bottom surface flattened circuit board back on the hot plate it heated up very rapidly, under a minute easily. I think most of the ones I tried were about thirty seconds. You had to use a fume hood on this step to not breathe the fumes. You can pick the components off the board on the hot plate or what I did was turn the board over and very gently tap them into a plastic bucket. With the components off but not the heated solder I then tapped the circuit board very hard on a large piece of glass. The heated solder will fly off, cool immediately on the glass, and then you simply scrap it off into a bucket for collection.

This method has its pros and cons like all the others listed here. You are hand processing the boards so you are exposed to fumes, heated surfaces, and flying metal pieces. You can though rapidly go thru a lot of circuit boards in a day if you desire and get all the steps down smoothly. I do use a band saw to cut larger circuit boards down to size to fit more easily on the hot plate. Here again cutting fingers off is a danger. 

Regards, Chris.


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## gold4mike

I know it's an old thread, but...

I just came from the local Goodwill store with an indoor electric grill. It takes about 3-4 minutes to get a motherboard hot enough to melt the solder and is large enough to heat approximately half the board at a time. I heat it up, turn it over and thump it on the edge of my wife's old turkey roasting pan. Almost everything falls off the board with one thump. The longer slots (PCI, ISA, AGP, RAM) are easily plucked off with a pair of needle nose pliers. The grill has a sloped two pan design that lets anything that falls off the bottom of the board drop under the top pan, keeping it from getting overheated by the element. 

This thing cost me $2.99 and I stripped 15 motherboards in less than 2 hours after work yesterday.

They also had a nice Pyrex casserole dish with lid for $1.00. The lab is coming together nicely!


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## Anonymous

Hey guys I know of another method.Its pretty easy to do,its extremely economical,super easy to obtain,and its even portable.Its a porpane camp heater.The one I am referring to is a directional heater that looks like a vertical stainless mixing bowl that sits on top of the small propane tanks.The dish and tanks are available at pretty much any walmart,or just about any type of camping or outdoor store.What I do is place a board in my bench vise and position the heater up against the board,but not too close or youll start burning the board before the solder starts to melt.You can see when the solder starts melting,so while holding the board with something(I use visegrips) that can keep your fingers away from the heat,you just hit the arm on the vise to release the board and tap it on something to pop the components off.If you try this methd I can save you a little time by telling you to make sure the board is not positioned directly over your vise,unless you are into the shiny silver plated vise look.Also if you place a device under the board to recover the solder make sure you move it before you take the board out of the vise or you may end up dropping components into your solder.


Johnny


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## Anonymous

I forgot to add something to to the blueprints for the tumbler from blueduck.Instead of a switch,to supply the power I would use a reostat,like an adjustable output for a ceiling fan.That way the rpm could be fine tuned to the most effective rate.

Johnny


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## blueduck

is this the used equipment that ya' all were talking about a couple years back?

http://www.usedequip.com/


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## steveonmars

I use an old toaster oven I paid $5 for at the flea market. You can get them at Goodwill real cheap. 

Just let it heat a minute and pick the board out with needlenose pliers and give it a whack on the inside of a 5 gallon bucket or something similar (I use a square cat litter bucket that's perfect) and then scrape off the monolithics and anything that doesn't fall right off with a putty knife. If you time it right you can use channellocks to pull the plastic PCI and memory slots off and leave all the pins still on the board, than heat a little more and the pins all fall off next ready to go right in the cell.

One thing I do for safety is pull the cylinder capacitors off that contain oil. When the oil inside them heats up it tends to smoke and I'd rather not breathe in those fumes if I can avoid it. It only adds a minute to the proccess but I think its worth it. I also only do this outside for ventalation. 

One nice thing is you can do this while you're doing something else while the boards heat up. Just don't forget to check the oven every minute or so or you can end up with a mess.

Steve


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## jevaud

Wow, excellent! Thanx for the post. This is exactly what I'm looking for.


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## jevaud

What about using a very hot blowdryer/ hairdryer to melt the solder, would it get hot enough... I don't think so but maybe it's worth a try. I do like the oven methods, I will have to look for a toaster oven.


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## patnor1011

i dont recomend hairdryer as most of them are fitted with overheating auto-disconnect switch. better option is heat gun. I was usin this but when depopulating with heatgun you are exposed to some fumes if board is overheated, also plastic connectors can melt and there is still solder left on your pins. tin can give you headache later when processing with acids. if you are doing it as hobby in spare time why not to use precicion snipers, and cut pins out. it is time consuming, sometimes you can get blisters but for start as perfect as anything else. when and if you will move to bigger amounts and more experience you can consider some other method which will suit you better. btw i am still cutting pins with knipex precision snipers...


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## jevaud

Sound like a plan. Yeah I kinda figure my regular house-hold scissors wouldn't cut it, lol pun intended. I have alot of old NES games too I don't play, I might as well throw those in as well. Now next will be finding something to dissolve the green film that cover the other trace metals on the board...


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## patnor1011

jevaud said:


> Now next will be finding something to dissolve the green film that cover the other trace metals on the board...



not worth, as there is mostly copper and if gold then only traces.


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## Anonymous

I know this thread might be dead but I am curious as to what method 7 is. Is it using a foundry furnace to melt everything?


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## Rhodium

Ogre_25 said:


> I know this thread might be dead but I am curious as to what method 7 is. Is it using a foundry furnace to melt everything?



Open burning !


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## Scott_Hawley

badastro said:


> Method 9: Hot acid bath
> Remove ferrous materials. Place boards in a bath of straight or diluted muriatic acid in a crock pot. Do not boil and keep it covered. The acid will attack all solder and leave gold and copper intact. The process should be over in less than an hour.
> 
> Pro: Method 9 is fast and efficient. It only dissolves the solder leaving behind components, a clean board, and dirty acid solution. Some people crock pot pins anyway...
> Con: It can produce acid fumes. Hot acid is dangerous. The spent acid is very toxic. *It is difficult of an average person to scale up.*



I am interested in using this method to depopulate tons of boards, but what does ths person mean it will be difficult to "scale up?"


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## Barren Realms 007

Scott_Hawley said:


> badastro said:
> 
> 
> 
> Method 9: Hot acid bath
> Remove ferrous materials. Place boards in a bath of straight or diluted muriatic acid in a crock pot. Do not boil and keep it covered. The acid will attack all solder and leave gold and copper intact. The process should be over in less than an hour.
> 
> Pro: Method 9 is fast and efficient. It only dissolves the solder leaving behind components, a clean board, and dirty acid solution. Some people crock pot pins anyway...
> Con: It can produce acid fumes. Hot acid is dangerous. The spent acid is very toxic. *It is difficult of an average person to scale up.*
> 
> 
> 
> 
> I am interested in using this method to depopulate tons of boards, but what does ths person mean it will be difficult to "scale up?"
Click to expand...


On a commerial scale with tons of boards as you have said you have it is not a viable option because of the amount of acid that is required. A way to heat the acid on a large scale. And disposal of the spent acid when this is done is costly. You would be better off finding a commercial buyer for your boards.


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## Claudie

I like the way each process is spelled out to make it easy to understand.


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## publius

perhaps this should be made a sticky. [/hint] :roll:


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## butcher

Remember you guy's heating the circuit boards that those electrolytic capacitors (the can type) they can explode, remove them first.


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## samuel-a

butcher said:


> Remember you guy's heating the circuit boards that those electrolytic capacitors (the can type) they can explode, remove them first.



Yup

This an important safety note.
Also the yellow/black tantalum cap's tends to pop quite violently...


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## CaptnCaveman

patnor1011 said:


> jevaud said:
> 
> 
> 
> Now next will be finding something to dissolve the green film that cover the other trace metals on the board...
> 
> 
> 
> 
> not worth, as there is mostly copper and if gold then only traces.
Click to expand...




I watched a video on lasersteves site that shows a process of removing solder mask from small board. I was thinking of using Method 5 (sand in a pan on a hot plate) to remove components and then try to remove the solder mask with the method he showed in the video, and then figure out the process to remove the gold traces from the board later(Im a noob learning). 

I am disappointed to hear it will mostly be copper under there. Would it still be good for me as a begineer to go thru this whole process to see the results or will I be very disappointed to find that 20 or so motherboards results in no visible product? If boards arent generally worth processing, what do you do with the cleaned off boards patnor..sell them in bulk to someone? I have your guide on how to process black surface mount chips and flatbacks...very appreciated!!


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## patnor1011

I would not bother with 20 motherboards. If you want to see some powder then try that method on some military grade or at least telecommunications equipment boards. Or some older network cards, soundblaster sound cards. Not many motherboards are gold plated under solder mask. 
You have to ask around for price of cleaned boards, they can be sold generally as low grade boards but yes they are still valuable and sell-able for their copper content.


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## glondor

I just posted this in another thread and then saw this one. Fits right in!

The best way I have found for depopulating is a reciprocating saw like a sawzall. Make a jig for your boards, get a scraper blade for the saw and go to town. I see the blades now are available up to 3 1/2 inches wide. Stuff flies everywhere!!. I just do it in a clean area and sweep up all the stuff after. I use various size sieves to sort it after. Some times I just buzz off certain parts then go after other parts later. With the right jig to hold the board you can spend more time switching boards than cleaning them off it is that fast. Watch out for kickback....Did 130 pounds of ram once in 2 days with just a 1 inch wide broken blade. 8)


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## kjavanb123

Great post, I am dealing with 50kg worth of boards weekly, so I am curios with that amount, what do you guys think would be the economical methods of depopulating the boards? I read this post but still can't find the optimum methods used by most people.

Regards,
Kevin


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## ericrm

im interested in number 7 ,what is it?


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## kjavanb123

All,

I used a steel sheet topped with some sands, placed the board solders on the sand, heat it up, and in less than 15 mins parts started to come off like a cake. even MCCs come off easily. without disturbing the plastic part of the board. Incredible advise from you all. Thanks
Here are some pics.





Thanks
Kevin


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## NoIdea

Evening, for some wierd reason i have not visited this post up until now. I remembered see/reading a automatic type depopulating PC type boards years ago, so i googled, and found what comes, sort of close, to what i remember.

http://www.patentgenius.com/patent/7703197.html

Happy Reading

Deano


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## kjavanb123

All,

After I removed the components off the board that contained PMs, I tested one of them believe is called a PCI socket, and put it in a 50/50 nitric / water solution and turned blue and after few mins the gold foils started to float around. Once the reaction stopped, I decant the blue solution, rinse with water few times till it becomes clear, decant, then dissolve the remain ( gold foils and some brown stuff ) in hcl / cl tablets, and immediately dissolved the gold foil at room temperature, heated it a little bit to get rid of chlorine, and gold dropped by addition of smb.

Tried the same component using hcl and nothing happened.

Regards,
Kevin


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## malfeces

Oh my god.....so many of my questions answered in one post!!! This forum ROCKS!!! Now I just need to find the thread that has a list a description (pics maybe) of the componants that are worth keeping!!! Thanks Lazersteve!!!!


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## etack

just about everything but the Al caps have value even the Al caps they can be put in breakage.

lots of threads on this.

old but good lots of link to more threads http://goldrefiningforum.com/phpBB3/viewtopic.php?f=33&t=6148

Eric


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## malfeces

Just to clarify, Method 7, the one that is not details, is it really incineration? There are many threads that talk about incinerating or "pyrolysis" method used on flatpacks and IC's. What componants become so illegally toxic? I only ask because I want to make sure I know what to avoid and why. Many thanks


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## Geo

malfeces said:


> Just to clarify, Method 7, the one that is not details, is it really incineration? There are many threads that talk about incinerating or "pyrolysis" method used on flatpacks and IC's. What componants become so illegally toxic? I only ask because I want to make sure I know what to avoid and why. Many thanks



all Escrap is considered toxic waste. once the equipment is broken down, it is Escrap. the EPA is lax on enforcing certain codes and strict on others. if you recycle the Escrap, theres little to no problem.if you start digging holes and burying it,big problem. anytime you heat PCB's (printed circuit boards) in the process of reclaiming metals, it releases phenols and other organic compounds that are considered toxic,harmful or cancer causing. if you do this on a small scale, like one or two at a time theres little to no problem.if you pile up a truckload and set it on fire,big problem.

if this is a hobby for you, stay small.if you want to start a business, go big, but be sure to stay within the law because the cost of cleaning up a toxic waste site will cost you everything and more and even put you in jail.


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## malfeces

Thanks Geo, knowledge IS power. This is just a hobby for me. This will remain small as I simply do not have the time or space to get any bigger and having two kids with special needs I need to keep a day job that has good health bennies. I do recycle everything. All the plastics I get from electronics get crushed and sent to a local single sort recycling facility. All the metals get sold to a almost local scrap yard. And all the other circuit boards were, until recently, going to the scrap yard for 10 cents a lb.... That is kind of my schtick, I place free ads here and there looking for broken computers and electronics and advertise that i specialize in destruction of all personal information on devices like cells, pcs, etc. I also let the people who give me scrap know that less than 2% of what I take in is sent to a landfill. Now a days there is a recycler for just about everything. I think it is very important that we all make out best effort to be environmentally friendly. 
Thanks again Geo!


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## cejohnsonsr

Hello all. I'm rather new to this, but have been doing a lot of study, including how to depopulate boards. I'm pretty sure I'd like to use the sand bath method. I saw a YouTube video of (I think) geo doing this with cell phone boards. Looked like a very efficient process. My question is, how hot do I need the sand bath to be? At what temp does the solder begin to melt? Thanks for any help & thanks so much to lazersteve & a few others who contribute so much here. 

Ed


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## Geo

from wiki : Soft solder is typically thought of when solder or soldering is mentioned, with a typical melting range of 90 to 450 °C (190 to 840 °F). [3] It is commonly used in electronics, plumbing, and assembly of sheet metal parts. Manual soldering uses a soldering iron or soldering gun. Alloys that melt between 180 and 190 °C (360 and 370 °F) are the most commonly used. Soldering performed using alloys with melting point above 450 °C (840 °F) is called 'hard soldering', 'silver soldering', or brazing.

http://en.wikipedia.org/wiki/Solder

my sand bath has a needle valve so i can adjust the heat and "hopefully" get the board hot enough to melt solder but not so hot as to make the board smoke. BE WARNED, even if the board isnt smoking, it is still evolving hazardous vapors that are toxic. in the video, i was demonstrating the bath but normally, i have a large squirrel cage fan blowing across my work.the fan was off because if it had been on, you couldnt hear what i was saying.


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## curtis.a

how would one process the powder from method 3 HCl then nitric then ar


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## lazersteve

General Reaction List

Section 8, item 1.) Cleaning and Drying Gold Powder

Welcome to the forum. You should read the entire Guided Tour link below

Steve


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## curtis.a

thanks steve ive been reading the forum for some time i was refuring to the powder from grinding the whole board HCl first for lead and tin nitric for silver, palladium, copper and AR for gold and platinum


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## cejohnsonsr

Thank you, Geo. I remember you mentioning the fumes & the fan in the video. I promise I'll set it up with positive airflow to move the fumes away from me & NOT toward anyone else. So about 400 degrees should do the trick I think. That helps a lot. Now all I have to do is decide on a heat source. Thanks again!

Ed


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## butcher

> Thanks steve I have been reading the forum for some time I was Referring
> to the powder from grinding the whole board HCl first for lead and tin nitric for silver, palladium, copper and AR for gold and platinum




curtis.a,
I am not sure what your question is about, but processing whole circuit boards is a bad idea.
When you say HCl first for lead and tin, you do understand lead will form insoluble salts of lead chloride, tin will form a gel that can hold fine gold, make filtering almost impossible, and if this was mixed with ground up circuit boards would just form one big mess.
Then you speak of using nitric acid; here you will just make a bigger mess dissolving your gold into solution (you would still have the chlorides involved).

Just making one big toxic deadly mess.

Grinding whole boards can be a process used industrially, but then you would have to treat them prior to using acids, by some other means such as gravity and mechanical separation, or adding a lot of copper and melting to impure copper bars or some other means.

You cannot just take one statement here (like grinding whole boards to powder) and use some other processes you read about to recovery or refine it using methods meant to refine other types of materials.

Begin with reading Hokes book, get an understanding of how to separate and process the many different types of materials, work on the getting acquainted experiments, to get a good understanding of how different metals react in solution, study the forum to learn how to separate your material and treat it with the several different processes needed (do not try and take one process and recover or refine it with a different process.

Study the forum and learn the processes used for each material, and the steps needed to do each process in recovery, and the following processes needed to refine the materials.

Start with the guided tour in the guide to the forum, and reading the welcome to new members found in the general reaction section.

Also study dealing with waste in the safety section, the safety and understanding this is the most important thing you need to understand.
What good will it do to get a gram of gold if you killed yourself trying to get it?


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## curtis.a

> [/Grinding whole boards can be a process used industrially, but then you would have to treat them prior to using acids, by some other means such as gravity and mechanical separationquote]
> 
> thanks butcher that is the info i was looking for im not doing it just researching I don't do anything till ive done a good bit of research on the subject.
> curtis


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## butcher

I believe industrially they separate mechanically as much as possible, and melt with scrap copper making impure copper anode bars (95% or greater in copper content) then ship these to the copper refiner's who electro win the copper to fairly pure copper cathode sheets, in huge copper refining cells, taking very large amounts of electricity, and current, to run these copper cells, precious metals end up as anode mud or slimes to be further processed for their values.


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## Pantherlikher

I've been kicking the idea of using a George Forman type burger grill with sand.
The large grill is big enough for mother boards and has raised ,grill like, surface witch sand can fill for a flat surface. It's also slightly tilted forward so solder sinking through the sand can flow out and into a catch pan. I'm not sure how hot they get but should be hot enough for solder.

I also had a wild thought of mylar grilling in this as the melted mylar would drain off leaving the silver traces. But not sure if it would melt or just burn the mylars causing bad fumes. 

BS.
Gotta love the cold winter as it puts off great experiments...


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## Geo

Pantherlikher said:


> I've been kicking the idea of using a George Forman type burger grill with sand.
> The large grill is big enough for mother boards and has raised ,grill like, surface witch sand can fill for a flat surface. It's also slightly tilted forward so solder sinking through the sand can flow out and into a catch pan. I'm not sure how hot they get but should be hot enough for solder.
> 
> I also had a wild thought of mylar grilling in this as the melted mylar would drain off leaving the silver traces. But not sure if it would melt or just burn the mylars causing bad fumes.
> 
> BS.
> Gotta love the cold winter as it puts off great experiments...



most types of heating elements like that only reach around 400 degrees F. if you add sand, it may not warm hot enough to melt solder but its worth a shot. who knows, it could be a "knock out". :lol:


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## butcher

Make sure you have some type of fume evacuation system so those fumes do not knock you out.


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## Buster

Hey Pantherlikher, let me know if this works for you, I might give it a go too if it does.


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## g_axelsson

The solder will not drain away, it is held in place by surface tension.
And the idea of leaving silver after melting off mylars doesn't work either, the silver is just a powder that crumbles when the plastic melts and mixes in with the plastic. It is actually silver paint made up of many small grains so it has no mechanical strength what so ever.

Göran


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## MMFJ

g_axelsson said:


> The solder will not drain away, it is held in place by surface tension.



In my experience (with soldering copper pipes and uncountable wires and electrical connections), it seems that any excess solder will 'flow' if kept hot enough, however, there will first be a layer of 'waste' (in this instance - perhaps 'unrecoverable' might be a better word?) which will coat the tray first, then the excess that is hot enough will flow away if the angle of the tray is high enough.

I'm not saying this is a useful concept (although very interesting, if it worked), simply that the excess solder would flow away (how much 'waste' would depend on the material the tray is made of - as stainless is hard to solder, there may not be any waste, though traces would always be there and any other attempts at recovery with the same tray would have contamination). 

And, while I consider the concept potentially interesting, it is impractical as the vast majority of 'excess' solder has already been trimmed from the boards in the original manufacturing process, which typically uses a capillary type action to draw UP the solder from a tray bath and therefore, doesn't lend itself to removal in the same manner (with the parts oriented on top). 

Perhaps, with enough agitation, some solder would come off enough to then remove the parts, but there will be parts that continue to hold on, etc. - using even more time later in processing by hand.

The (MUCH) simpler idea is to take the board into an 'oven', upside down (where the parts will fall as they heat enough to melt the solder) - agitating along the way (my vision is a pizza type oven with a 'cobble-stone road' (something to cause as much bouncing around as possible - could be oblong wheels, a board full of screws/nails at different heights - anything to make it shake as it goes through). 

The board should come out clean - other than some transformers, etc. that have parts/pins folded over, which will have to be physically removed.

One challenge here is that the parts will have hot solder on the legs and may want to stick to other pieces. My thought on this is to keep a moving belt (more like a series of small trays that are close enough to touch when under the boards and then dump the contents as they pass the end and turn upside down upon return) going in the opposite direction - that should eliminate that problem. However, it should first be proven this is an issue - it may be that simply keeping a collection tray low enough to allow for cooling will keep the parts from sticking too much (I tend to over-engineer things and then test alternatives before building the 'ultimate' contraption!) 



g_axelsson said:


> And the idea of leaving silver after melting off mylars doesn't work either, the silver is just a powder that crumbles when the plastic melts and mixes in with the plastic. It is actually silver paint made up of many small grains so it has no mechanical strength what so ever.
> 
> Göran



I've also experimented with mylars, melting them slowly, and did find silver there, in 'solid' form. I followed the method http://goldrefiningforum.com/phpBB3/viewtopic.php?p=6388#p6438 - however, I believe (though have not tried it) that a diluted nitric wash (also discussed in that thread) is a better idea.


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## gold4mike

MMFJ,

I like your "pizza oven" idea and have used a smaller more manual version of it. I use a small electric grill to heat the bottom of the board until I can move parts around on top. I grip the board with pliers, turn it over and thump it on the edge of a large porcelain/metal baking pan. Most of the parts come off and some of the smaller MLCC's and such do, as you mentioned, get stuck in some of the solder that comes off as well. 

I'm thinking of building a shear using something similar to a wood splitter as a basis. I envision a large piece of metal with a precise 90 degree angle edge, resting on the surface of the board, then shoving it along the surface, plowing off all the parts into a catch pan at the end. 

The board would rest against a stop at the far end of the duty cycle of the ram and lie flat on a heavy steel plate. The distance between the plate and the ram with the metal block would have to be able to be increased or decreased to compensate for the different board thicknesses and the length of the portion of pins that stick through the board on the bottom.


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## mjgraham

I have been depopulating boards today and I ended up using a convection oven ( not for food again ) goes to 550F about 5 min in and good slap, something I made for the MLCCs and such was to take some 1" Al flat bar and build a frame that had a gap that the board would fit through and while it is hot slide it though it, gets the rest off or go at it with a scraper while hot, working pretty good. Better than the heat gun , while it works much slower.


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## butcher

Remember the tin in solder will dissolve gold into it, making an almagam of tin and gold, even at temperatures as low as the melting point of the solder.

Free melted solder will also solder to other (unsoldered metals) before it will drip off.


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## mjgraham

Oh yea I have a mess of parts , but sorted the chips ,tantalum caps, and the other into piles (solder, MLCCs and other small parts) , of course I have removed non PM stuff already, and I guess I should say any electrolytic caps get tore off before the heat. I guess getting the parts off is the easy , fast part the rest is slow and steady and hopefully not sad in the end. Most of these boards were gold plated so now there a soldery smeary mess that gets some HCl for a while.


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## Geo

gold4mike said:


> MMFJ,
> 
> I like your "pizza oven" idea and have used a smaller more manual version of it. I use a small electric grill to heat the bottom of the board until I can move parts around on top. I grip the board with pliers, turn it over and thump it on the edge of a large porcelain/metal baking pan. Most of the parts come off and some of the smaller MLCC's and such do, as you mentioned, get stuck in some of the solder that comes off as well.
> 
> I'm thinking of building a shear using something similar to a wood splitter as a basis. I envision a large piece of metal with a precise 90 degree angle edge, resting on the surface of the board, then shoving it along the surface, plowing off all the parts into a catch pan at the end.
> 
> The board would rest against a stop at the far end of the duty cycle of the ram and lie flat on a heavy steel plate. The distance between the plate and the ram with the metal block would have to be able to be increased or decreased to compensate for the different board thicknesses and the length of the portion of pins that stick through the board on the bottom.




https://www.google.com/url?q=http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php%3Ff%3D60%26t%3D10822%26view%3Dprevious&sa=U&ei=Tb4SUdbMMrG_2QXnrYG4DQ&ved=0CAcQFjAA&client=internal-uds-cse&usg=AFQjCNHYWqUgTMdGh9p_KkRe_H1F2TMNAw


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## butcher

HCl + Tin = Stannous Chloride
HCl + Tin + Gold in Solution = Colloidal Gold
Keep the oxidizers out.

I have always like that idea of the hydraulic Shear to remove parts from the boards.


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## gold4mike

Thanks Geo - I forgot about that post.

It might be a better idea than the one in my head  

A very similar idea...


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## mbflash

butcher said:


> Remember the tin in solder will dissolve gold into it, making an almagam of tin and gold, even at temperatures as low as the melting point of the solder.
> 
> Free melted solder will also solder to other (unsoldered metals) before it will drip off.



So would i be better off cutting pins off than heating to unsolder them?
I would be using a cell for the pins.
Also Geo responded to a post by someone asking about treating pins with HCl pryer to going
to the cell he said something like not to bother. 
Am i correct in assuming the small part of almagam (tin and gold) that part of gold would not be
recovered in the Sulfuric cell ?


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## kilo17

I use Steve's method with the AP. I save and reuse my AP several times and when I have accumulated to much from additions, I pour it off into a second bucket that I use to depopulate RAM boards etc... Here are a couple of pics from some I did this weekend.


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## total-resale

For the small timers, i found a medium size chisel is great but i dont use it as you would normally I place it beside them and twist my wrist, it is labor intensive but I do sets of components at a time so no sorting. IC's first, use edge of chisel to cut legs then use leverage from beneath, Caps and Res with the twist, can do a stick of ram in a minute and very little mess. Safety glasses as must (as should be normal) Had a tiny resistor fly up my nose and im not sure i ever found it =( now I wear a dust mask.


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## danogarvin123

Besides the obvious of de-populating PCB's for the IC's.......what other value is it? I only pull the IC's and pins off for future recovery...and then toss them into my pile for e-scrap. Am I missing some valuable recovery items?


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## squarecoinman

danogarvin123 said:


> Besides the obvious of de-populating PCB's for the IC's.......what other value is it? I only pull the IC's and pins off for future recovery...and then toss them into my pile for e-scrap. Am I missing some valuable recovery items?




Yes you are missing a few things, monolithic ceramic capacitors , tantalum 

Use the search on the forum , it will be a good exercise for you and it will explain why you should keep the MCC and the Tantalum capacitors 

scm


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## danogarvin123

SCM.....thanks for the insight...and the extra work. Seems I need to go back through my e-scrap bin and begin de-populating...again. Glad I tend not to throw anything out.


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## hatemelborai

The best method is to use fluoroboric acid and hydrogen peroxide to strip solder, the you can remove all components easily.


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## kazamir

hatemelborai said:


> The best method is to use fluoroboric acid and hydrogen peroxide to strip solder, the you can remove all components easily.



Can you please elaborate on this process.


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## patnor1011

kazamir said:


> hatemelborai said:
> 
> 
> 
> The best method is to use fluoroboric acid and hydrogen peroxide to strip solder, the you can remove all components easily.
> 
> 
> 
> 
> Can you please elaborate on this process.
Click to expand...


Better not to.


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## hatemelborai

patnor1011 said:


> kazamir said:
> 
> 
> 
> 
> 
> hatemelborai said:
> 
> 
> 
> The best method is to use fluoroboric acid and hydrogen peroxide to strip solder, the you can remove all components easily.
> 
> 
> 
> 
> Can you please elaborate on this process.
> 
> Click to expand...
> 
> 
> Better not to.
Click to expand...


to strip solder, solution of fluoroboric acid 40% of 30-50 percent by volume and hydrogen peroxide 30% of 7-10 percent by volume and balance with water, heat the solution to 60 c. it will take about 4 hrs to remove the solder


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## Captobvious

hatemelborai said:


> patnor1011 said:
> 
> 
> 
> 
> 
> kazamir said:
> 
> 
> 
> 
> 
> hatemelborai said:
> 
> 
> 
> The best method is to use fluoroboric acid and hydrogen peroxide to strip solder, the you can remove all components easily.
> 
> 
> 
> 
> Can you please elaborate on this process.
> 
> Click to expand...
> 
> 
> Better not to.
> 
> Click to expand...
> 
> 
> to strip solder, solution of fluoroboric acid 40% of 30-50 percent by volume and hydrogen peroxide 30% of 7-10 percent by volume and balance with water, heat the solution to 60 c. it will take about 4 hrs to remove the solder
Click to expand...


Me thinks I'll just stick with my heat gun... much simpler... quicker too


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## patnor1011

Yep, not to mention that above process just create additional waste stream needed to be dealt with. Heatgun allow you to collect solder which can be sold or used.


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## ldpolli

Very old subjetc, and i saw this in some website, is it possible working with pcb? Or ic's? Maybe dissolve epoxi?

Anyone knows anything about this? Already tryed?

http://www.ecycle.com.br/component/content/article/37/343-maquina-transforma-plastico-em-oleo-livre-de-co2.html


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## marlyn

> Method 10: Thermal depolymerization



Does anybody have some experience with this process? I like the idea very much, but I'm not sure about economical part. Even in small scale production/own equipment. Not talking about 4MPa pressure and high temperature...


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## patnor1011

ldpolli said:


> Very old subjetc, and i saw this in some website, is it possible working with pcb? Or ic's? Maybe dissolve epoxi?
> 
> Anyone knows anything about this? Already tryed?
> 
> http://www.ecycle.com.br/component/content/article/37/343-maquina-transforma-plastico-em-oleo-livre-de-co2.html




That kind of machine is nothing new. It is rather expensive and if you are going to buy it you will better stick to what it is designed for. It work with certain type of plastic only so I guess sticking printed circuit board in it will not be advisable and practical. I would compare that to ore crusher and coffee blender. Action look the same but you cant use one of them for both materials.


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