# depopulating cell phone boards



## Geo

this is an ongoing project for me. i started out with a Coleman burner and a cast iron skillet and was only able to do two at a time. i soon realized that i would need to move to big and better quickly. the burner is a LP radiating heater laying on its back. i do understand the dangers in this and keep a rated fire extinguisher on hand when operating. i installed a needle valve inline to regulate the gas flow because the heater only has off and on. i thought it may be helpful to some newer members to see a sand bath in action. i depopulated a pile of PCI cards with it as well and it worked like a charm.being able to turn the gas down should save on fuel consumption.i hope some of you find some helpful information from it and i will add to it as the project continues.

[youtube]http://www.youtube.com/watch?v=Pn5LjwnmYFg&feature=plcp[/youtube]


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## coppermine

Cool!! I've been racking my brain for s ome time on this subject. Thanks for the post!


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## Geo

this is following along with the cell phone boards.[youtube]http://www.youtube.com/watch?v=bgxMqM42n6A&feature=plcp[/youtube]

[youtube]http://www.youtube.com/watch?v=Ef15J6wVcP8&feature=plcp[/youtube]

[youtube]http://www.youtube.com/watch?v=8P58ofyYrz0&feature=plcp[/youtube]


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## ericrm

Very, very nice Geo
each time i think im good on the recovery race ,someone like you just show me that, im in fact just behind someone. keep on the fantastic job


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## rewalston

Geo, I'm assuming that the components seen in video 2 are from when you desoldered the boards correct? And then anything that was larger than the 1/4" went into your incinerator? Looks like a very good setup. What did you do with any excess solder that were on the boards before you put them into AP or did you not worry about it? And I would assume that when you incinerate the other components, that it will talk care of any solder that is on them as well?

Rusty


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## Geo

correct, all the components came from the sand bath.after incinerating and removing the iron, ill wash as much ash out of the remaining material as i can. then all the remaining material will go through a hcl bath to remove as much tin as i can before AR. the boards went through a hcl bath prior to the AP. i make a solution of 1 part hcl and 3 parts water. the boards came out pretty clean. theres still some sand in the components from the sand bath. that means ill have to screen it again to a smaller size to remove the remaining sand and all the tiny MLCC's.


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## mjgraham

Pretty nice, I love the simple but effective approach, plus the free info is great also.
Thanks


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## rewalston

Geo, you're using AR, but I'm not able to (yet). Do you think HCl/Bleach would work ok?

Rusty


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## Geo

it will work fine for the foils.the components can be run in AP too, but it tends to take forever because of the iron content. the only real challenge would be the flatpak chips. even though the bonding wires are small, it may be difficult to dissolve them in hcl/Cl. im not sure about that because i have never tried.there are some chips in the components that ive seen on larger electronics that appear to be a small ICB under a small copper cap with gold colored braze.ill pick out a couple and post pictures of them. i cant imagine processing them without AR.


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## ovidiuanghel

Geo, how many boards do you have in AP?


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## Geo

i didnt get an exact weight, but it was two 5 gallon buckets level full of depopulated phone boards. ill put some more video up as soon as they have completed the AP.


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## goldenchild

These videos where HIGHLY entertaining! The sand bath is a sweet way of depopulating the boards without flames. I will be keeping an eye on this thread. Nice work. 8)


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## tomiyet

Geo, I'm a newbie and in few days I've been able to read a lot from this forum. I guess this is d 3rd time I'm reading ur thread maybe due to the mess on my cell phone boards like over 200 pieces. There is unanswered question and thought in my mind, "What chemical can dissolve the whole cell phone boards at a go" though I'm not able to view ur video but like my experience in silvery recovery caustic soda solution will dissolve all silver coated on xray films in less than 1hr. I just finished reading Hoke's book 'awesome' but I think I need a direction on hiding values on boards. Thanks


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## jimdoc

tomiyet said:


> There is unanswered question and thought in my mind, "What chemical can dissolve the whole cell phone boards at a go"



Although that may seem the easy way to do it, it is the making of a big mess and more hassles for you in the long run. 

Jim


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## malfeces

Excellent thread Geo!! I have read it many time and watched your videos over and over. I am a major visual learner. I am wondering if you know roughly what temp your bath is at? I have a stainless steel electric skillet I was thinking of trying with sand. It only hits 450 though...


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## Geo

malfeces said:


> Excellent thread Geo!! I have read it many time and watched your videos over and over. I am a major visual learner. I am wondering if you know roughly what temp your bath is at? I have a stainless steel electric skillet I was thinking of trying with sand. It only hits 450 though...


 
i have a IR thermometer that i can use to check with the next time i fire it up. just off the top of my head though, id say pretty darn hot. :lol: i know thats not what your looking for, but normally, i crank it wide open and then gradually turn the heat down with the needle valve. i found that with the burner running wide open, it made my cast iron griddle sag in the middle badly. it was close to the point of the middle collapsing out of the pan. if it can hit that happy medium where the solder melts and before the board starts to smoke is where i want it to stay. 

be aware that even though the board isnt smoking, if it gets hot enough to melt solder, its still gassing off phenols and other organic vapors that are very unhealthy. be sure there is a good breeze blowing across your work (not from behind or in front) even if you have to set up a strong fan or blower.i have several i use and the reason it wasnt shown in the video was because if it had been running, it would have been the only thing heard.


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## butcher

About 700 degrees F is a good temperature for melting solder with an soldering iron with a temperature dial.
http://en.wikipedia.org/wiki/Solder


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## AndyWilliams

Great videos Geo, they help a great deal. I do have a couple of questions, just for clarification, because I have not done any of the processes.

1. In the 55 Gallon drum, is that where you processed the boards?
2. You said it was Copper Chloride, is that the AP process?

Thanks in advance.


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## Geo

AndyWilliams said:


> Great videos Geo, they help a great deal. I do have a couple of questions, just for clarification, because I have not done any of the processes.
> 
> 1. In the 55 Gallon drum, is that where you processed the boards?
> 2. You said it was Copper Chloride, is that the AP process?
> 
> Thanks in advance.



1. yes. there was two five gallon buckets level full of boards. the drum was the only way to process them all at the same time.
2. yes. AP is the general term for the process. the peroxide is just to dissolve the first small bit of copper in the hcl. hcl alone does not like to dissolve copper.copper chloride will dissolve (etch) copper rather quickly when in the presence of free oxygen. thats why we bubble air through the solution.


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## Marcel

The sand bath is (another) good idea of yours. In the times of wavesoldering, before SMD came through sandBAGs were sometimes used to transfer heat to the PCB. Maybe you can improove your process that way as well, no more sandparticles on your board. Just find a heat resistant fabric and put that fine quartzsand into a bag. 
If the boards are populated from both sides, they will rest on the bag and you can just pick/wipe them off without having sand on them.
Instead of propane you could as well use a hotplate!
Marcel


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## Geo

thank you Marcel.good ideas and worth investigating. sand stuck to the board really doesnt matter, its the sand that gets mixed in with the very small components that is a nuisance. trying to separate the sand from the tiny SMD's. i suppose this may not be an issue since they are processed with nitric acid.


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## BJL1984

I know this may sound a little odd, But a good idea for a heat resistant material for the sand bag might be an asbestos blanket like a plumber would use to protect combustible materials close to where he has to solder a pipe, never tried it in a sand bag capacity, but i have used them at work and put a mapp gass torch right to it and it only blackens a little bit, not sure how common they are new asthe one i keep in my tool kit is about 40 years old, but if you cant find one made from asbestos, I am sure there is an enviromentaly safe alternative on the marke fo the same purpose cant hurt to go to your local plumbing supply house and ask


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## etack

Geo said:


> thank you Marcel.good ideas and worth investigating. sand stuck to the board really doesnt matter, its the sand that gets mixed in with the very small components that is a nuisance. trying to separate the sand from the tiny SMD's. i suppose this may not be an issue since they are processed with nitric acid.



Try wool it wont burn at that temp but will brown and get brittle over time.

Use thin pieces like from suits this will allow the heat to pass through it and do its job if its to thick you will waist heat.


And at the end of the day it can be burnt with open flame.

Eric


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## butcher

What about a thin layer of ceramic fiber wool (furnace fiber glass wool), it will burn to glass flux.


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## Auggie

Place them on top a high temperature sheet of glass (like for in front of fireplaces) and heat up the glass with a flame(?)


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## Geo

i tried a bag made of fiberglass cloth used in auto body repair. it seemed to work ok, but i had to turn the heat up higher than if i had just used sand.


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## butcher

Hmm I wonder how Noxx's Teflon coated electric skillet would do, but we better not scratch it.


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## BJL1984

Teflon Pedistal Kinda like a porclian throne, sorry bad joke but i couldnt help my self


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## glondor

I don't think an electric skillet will get hot enough. The 2 I use only get to the 380- 400 degree range F as checked with a laser thermometer. I know when I did a bunch of Nortel aluminum gold plated rf shields, the pans were barely adequate to soften the glue between the block and circuit board. The board comes off and it is plated on the back, as well the block is plated on that side. 2 extra GP surfaces if you separate the pieces. Heat was the solution, but the pans were not quite hot enough at 400 degrees. No components were desoldered, as there was not enough heat.


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## chevyman_76

Hello all,

Currently I'm very new to all this and learning through all that you guys have on this forum which is quite extensive (GOOD STUFF). Please pardon my questions as I said I'm new to this.

Right now I'm doing mostly Computer Boards and would like to know if in the picture above the PLC boards to the right is that gold lines on the board as I thought it was just the connectors on boards that were gold bearing (plated).

Geo, Question for you and sugestion as well.



Geo said:


> AndyWilliams said:
> 
> 
> 
> Great videos Geo, they help a great deal. I do have a couple of questions, just for clarification, because I have not done any of the processes.
> 
> 1. In the 55 Gallon drum, is that where you processed the boards?
> 2. You said it was Copper Chloride, is that the AP process?
> 
> Thanks in advance.
> 
> 
> 
> 
> 1. yes. there was two five gallon buckets level full of boards. the drum was the only way to process them all at the same time.
> 2. yes. AP is the general term for the process. the peroxide is just to dissolve the first small bit of copper in the hcl. hcl alone does not like to dissolve copper.copper chloride will dissolve (etch) copper rather quickly when in the presence of free oxygen. thats why we bubble air through the solution.
Click to expand...


1. Is that all cell phone and PLC computer cards? Can you do mother boards too?
2. You refer to AP (?) what is this? If you are mixing Hydrogen Peroxide and Hydrocloric Acid what are the ratio's per gallon you were using in your video? What and where do you find Copper Cloride, and at which point do you use it, after incenderating the remainders of the scraps (why do you do this if it is just scrap).

OK now with the tip for your furnace. Being a industrial boiler operator there is some things you can use to retain heat and prevent burning out the side of the furnace. In boilers there is what is called refractory to prevent burning out of the metal around the burner. This refactory can be found as plaster to coat the interior of your furnace to prevent burn out. Also placing those ceramic tiles you buy for distributing heat in a BBQ for even cooking can be placed around your furnace to presurve more heat consumption and reduce fuel required. 

Hope that last bit helps.
I'm currently depopullating PLC Boards, Cell Phones and Mother Boards to process and want to get my ducks lined up in a row
Chevyman_76


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## Geo

1. just cell phone boards. kind of disappointing yield on those too.

2. AP is acid/peroxide. it is covered in many places on the board. it can be used to dissolve base metal to liberate gold foils from boards or pins.look here to become acquainted.https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CFIQFjAB&url=http%3A%2F%2Fgoldrefiningforum.com%2F~goldrefi%2FphpBB3%2Fviewtopic.php%3Ff%3D52%26t%3D12914&ei=wMvlUP2FOJKy9gSZx4HgAQ&usg=AFQjCNHwWq2fZ-EAkhgbj8QvWMucEdGz3g&bvm=bv.1355534169,d.eWU

copper chloride is created during the process. creating and maintaining copper chloride takes some practice but it can dissolve an amazing amount of copper in its useful lifetime.

the gold on the board (gold plated traces) is only about a third of the gold in a cellphone. the components hold the other two thirds. they need to be incinerated and milled or crushed to get to the gold hidden inside.


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## damezbullion

Just a quick one, can i use this process to depopulate my memory/ram borads? same things isnt solder on components, i dont even know why im asking but just making it clear, would this also eliminate some use of a hlc leach before (ap)? cheers


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## Geo

damezbullion said:


> Just a quick one, can i use this process to depopulate my memory/ram borads? same things isnt solder on components, i dont even know why im asking but just making it clear, would this also eliminate some use of a hlc leach before (ap)? cheers



yes, it can work for any printed circuit board. the sand bath will not remove all the solder but it does remove all that will shake loose when its melted.if tin in your AP concerns you then you should do the hcl bath anyway but honestly, after you remove the components and all the loose solder the small amount of tin left will oxidize in the AP solution in a short amount of time anyway. i dont believe it will hurt to put a little tin in the AP as long as you know how to deal with tin oxide when the need arises.


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## rewalston

Geo said:


> i dont believe it will hurt to put a little tin in the AP as long as you know how to deal with tin oxide when the need arises.



Jeff can you explain how you would deal with the tin oxide? I've been reading the whole board but I think I might have missed dealing with tin oxide.

Rusty


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## damezbullion

Geo said:


> damezbullion said:
> 
> 
> 
> Just a quick one, can i use this process to depopulate my memory/ram borads? same things isnt solder on components, i dont even know why im asking but just making it clear, would this also eliminate some use of a hlc leach before (ap)? cheers
> 
> 
> 
> 
> yes, it can work for any printed circuit board. the sand bath will not remove all the solder but it does remove all that will shake loose when its melted.if tin in your AP concerns you then you should do the hcl bath anyway but honestly, after you remove the components and all the loose solder the small amount of tin left will oxidize in the AP solution in a short amount of time anyway. i dont believe it will hurt to put a little tin in the AP as long as you know how to deal with tin oxide when the need arises.
Click to expand...


i found out the hlc wont be such a pain after all, so ill put it all in a bucket and leave it a few hours, i dont really wanna mess around with tin, and no im not to clued up for it, i learnt how to drop silver out of an (ar), so if i just eliminate all the solder first, the im basically working with clean golden fingers and ill just proceed with my ap, and might even process the flatpacks.
today i bought 500 ram sticks, 9 kg so roughly 18 lb, i paid a whack of £175 including delivery, also by tommorow i shall have 6 ceramic Pentium pro ( holy Grail ) and 3 kg of cpu 51 of them are ceramaics ranging from m11 and Pentium dx,
so befor long i will start my story topic on the procceses throught this with pics hopefully, iv put around £500 into this project including materials tho im off to buy them tommorow, your going to be tutor geo from ram sticks to buttons 

i will follow ideeditdoes tutorial to process all my ceramic cpu, the nitric way it seemed a solid way, my ram sticks i will hlc leach followed by lazers steve finger foil tutorioul, ( poot man ar ) also might have a crack at the fltpacks( but i have no furnice ), also will have some fibre cpu which i think i will follow same route as my ram sticks ( hlc leach then ap/pins seperatly)then i will refine everything together.

im not sure but i got a feeling i could get a ounce out this i tried to dumb down my expected gold recover but it still seemed high, i know i should pull at least 6 g from my pentium, plus i have another 50 ceramics at 0.1g each thats still 5g plus all the fibre cpue green and black up to 3kg, and 9kg of ram sticks, i should get at least a gram a lb or 2g kg thats 18g in total ?


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## Geo

rewalston said:


> Geo said:
> 
> 
> 
> i dont believe it will hurt to put a little tin in the AP as long as you know how to deal with tin oxide when the need arises.
> 
> 
> 
> 
> Jeff can you explain how you would deal with the tin oxide? I've been reading the whole board but I think I might have missed dealing with tin oxide.
> 
> Rusty
Click to expand...


if you reuse the AP solution long enough,the tin that is introduced basically converts to stannous chloride in AP.in the presence of oxygen, stannous chloride converts to tin oxide.this collects as a white powder in the solution and mixes with the other powders and foils.after the foils and powders are collected, it should all be incinerated.this helps drive off the extra oxygen atom in the tin and making it soluble in hcl again.after incinerating, give all the material a hcl bath and heat.this will remove the tin from the material for further refining.


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## rewalston

Geo said:


> rewalston said:
> 
> 
> 
> 
> 
> Geo said:
> 
> 
> 
> i dont believe it will hurt to put a little tin in the AP as long as you know how to deal with tin oxide when the need arises.
> 
> 
> 
> 
> Jeff can you explain how you would deal with the tin oxide? I've been reading the whole board but I think I might have missed dealing with tin oxide.
> 
> Rusty
> 
> Click to expand...
> 
> 
> if you reuse the AP solution long enough,the tin that is introduced basically converts to stannous chloride in AP.in the presence of oxygen, stannous chloride converts to tin oxide.this collects as a white powder in the solution and mixes with the other powders and foils.after the foils and powders are collected, it should all be incinerated.this helps drive off the extra oxygen atom in the tin and making it soluble in hcl again.after incinerating, give all the material a hcl bath and heat.this will remove the tin from the material for further refining.
Click to expand...



OH DUH :lol: I remember that, boy do I feel foolish

Rusty


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## damezbullion

rewalston said:


> Geo said:
> 
> 
> 
> 
> 
> rewalston said:
> 
> 
> 
> 
> 
> Geo said:
> 
> 
> 
> i dont believe it will hurt to put a little tin in the AP as long as you know how to deal with tin oxide when the need arises.
> 
> 
> 
> 
> Jeff can you explain how you would deal with the tin oxide? I've been reading the whole board but I think I might have missed dealing with tin oxide.
> 
> Rusty
> 
> Click to expand...
> 
> 
> if you reuse the AP solution long enough,the tin that is introduced basically converts to stannous chloride in AP.in the presence of oxygen, stannous chloride converts to tin oxide.this collects as a white powder in the solution and mixes with the other powders and foils.after the foils and powders are collected, it should all be incinerated.this helps drive off the extra oxygen atom in the tin and making it soluble in hcl again.after incinerating, give all the material a hcl bath and heat.this will remove the tin from the material for further refining.
> 
> Click to expand...
> 
> 
> 
> OH DUH :lol: I remember that, boy do I feel foolish
> 
> Rusty
Click to expand...

 so am i right in believing if i collected the tin oxide, can washed and used as stannouse? simly?


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## Geo

i wouldnt.when making and using test solution or standard test solution, you should use the most pure components that you can acquire. the cost of the new material is nothing compared to the assurance that what you are testing with and against is what it is suppose to be. using scrap material to make test solution is not a good idea because there will be other metals and contamination that may throw off the test or change the results causing more harm than good.


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## damezbullion

Geo said:


> i wouldnt.when making and using test solution or standard test solution, you should use the most pure components that you can acquire. the cost of the new material is nothing compared to the assurance that what you are testing with and against is what it is suppose to be. using scrap material to make test solution is not a good idea because there will be other metals and contamination that may throw off the test or change the results causing more harm than good.



thankyou good point i only ask as stannous seems expensive, but doesn't cost as much as my precious metals lol

and what about the hlc is tin all that dissolves, if so and precipitates can i reuse my hlc or is no good?


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## Geo

that the good thing and bad thing about stannous chloride.given time in an open container,it will oxidize to tin oxide and fall out of solution. the hcl bath can be used (as a bath) over and over until the acid is depleted or so fouled it will not hold more metal.if it is saturated with tin and the PH is still 1 or 2, let it sit undisturbed and the tin will fall out and you can start over again.tin oxide is resistant to attack by hcl and will not dissolve in hcl.

stannous chloride is actually very cheap to prepare your self.just dissolve a known piece of tin metal in hcl and you have your stannous chloride.i use 95/5 tin/antimony solder and dissolve several grams in 30 ml's hcl at a time.if all the metal dissolves,add a little more metal until no more dissolves.keeping a little metallic tin in your SnCl keeps it active longer.

also,be sure to make a gold standard test solution to test your stannous against.its a solution known to contain gold (AuCl) to test your stannous periodically because it does have a shelf and storage life.once the tin converts to oxide,it will not detect metals in solution.

if you process some metal that you suspect contains precious metal and you test and the test is negative,test the stannous with your gold standard test solution to make sure the stannous is active.


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## damezbullion

this worries me, i have just purchased some gold testing stounnous from a jewelers already diluted as it seemed expensive to buy, i wish i just bought a peice of tin now lol and i get why cant use you hcl batch for you stannous now ( it will contain more than just tin ) thanks geo, im just waiting on my equipment now , my hydrochloric is out of stock so had to buy 36% but this should be fine right, my auction for the last of my scarp ends in 10 mins, hope i get a bargain


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## damezbullion

Dan i lost them i wasnt paying $170 for 50 ceramics and 70 fibre ceramis, they was all low yeilders to maybe o.25 the highest, so i got 2 more chance at some ceramics i think i will go for, one of them has a Pentium pro in it and a amd k5 pluse  plus 4 m2 and 4 cyrex 686 not a bad find , at least now i havnt got to bother with fibre cpu, i really didint wanna bother with them


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## squarecoinman

Geo I just wanted to let you know that I am enjoying your videos, soon I will try to built a small incinerator 
but for now the weather is still to bad ( Denmark we still have snow ) 

scm


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## Geo

thank you squarecoinman. this is such a great forum that i try to help and contribute when i can. i hope you found the videos helpful.


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## squarecoinman

Geo said:


> thank you squarecoinman. this is such a great forum that i try to help and contribute when i can. i hope you found the videos helpful.



Geo ; I do find the videos helpful , First I did read Hoke and now i am reading the forum post backwards , but the videos help as sometimes it is so much easyer to see things thanks for that 

scm


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## TheGoldFart

Hi everyone. This will be my first post on this forum. Glad to meet you all.
I am wondering if there is anything inherently wrong with using a kiln with a digital temp controller for this depopulating application. I do glass blowing so I also do have adequate ventilation. 
If this would work @ what temperature does the solder melt? I would probably go 20 or so degree higher than that just to make sure the entire kiln is at a consistent melting temp.


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## squarecoinman

TheGoldFart said:


> Hi everyone. This will be my first post on this forum. Glad to meet you all.
> I am wondering if there is anything inherently wrong with using a kiln with a digital temp controller for this depopulating application. I do glass blowing so I also do have adequate ventilation.
> If this would work @ what temperature does the solder melt? I would probably go 20 or so degree higher than that just to make sure the entire kiln is at a consistent melting temp.



Melting temp for soft solder is between 90 and 450 Celsius. Putting phone boards in your kiln may work, but I would put sand on the floor so I would not get solder in the kiln, and I am not sure if it will be practical to get the boards in and out of the kiln, then of course I would consider how much will it cost me in electricity.

Since you are new here you should take the guided tour ( Find lazersteve, there is a link in his signature ) and you should also read Hoke you can download that for free at the forum ( use search to find it ) 

scm


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## Geo

consider your heat source. in the video, i am using propane to warm the sand which then warms the components on the board. you really dont want the boards to smoke for a couple of different reasons. the first and most important is safety. the boards contains really,really nasty stuff. it is toxic to breath and can be absorbed through the skin. having these organic vapors enclosed is a very dangerous thing to do. as mentioned before, i had a large squirrel cage blower blowing across the sand bath as we worked blowing down wind. the second reason is the vapors can be explosive. if it creates the right fuel/air ratio with the tiniest ignition source, it will explode whether its contained or not. the third and least important but also the most troublesome reason is you dont want the components to be over heated.these tiny pieces are hard enough to deal with without them crumbling into giblets or powder or the plastic parts melting all over everything.

bottom line is, if the board smokes, you have it too hot.


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## Smack

GoldFart, don't use the kiln, find a better method like a stove/oven and set it at 400 or a little over.


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## TheGoldFart

@Geo - I did try one cell phone board in the kiln before I came back to your response. Based on your suggestions and my experince I just wanted to come back and state that I will not be using it again. I did not smoke the board however I did find that it just doesnt heat the components evenly across the board. I had to put it back in several times to get all the components off. Probably has to do with the fact that the heat source comes from the sides of the kiln and not from the bottom.

@ squarecoinman - just an FYI regarding electricity use. Its really not that bad. I use my kiln at much higher temps to anneal glass at least 8-10 hrs/week and my electric bill is maybe $10 higher a month. Though it would probably be higher with a fabric insulated kiln rather than the brick kiln I use.

*edit* I just remembered I have a barrel style propane turkey smoker in my shed. Im going to see if I can rig it up similar to your sand bath.


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## Dwsj65

Kicking up an older thread here, but one of great interest to me. Geo, I just wondered if you videoed the rest of this process? I am such a visual learner, and the videos in this thread were just the thing for me, but then it seemed to die "mid-process". Thanks


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## Geo

actually, the entire process was recorded but only a few of the videos made it to my youtube channel. the camera along with the rest of the videos was stolen from my vehicle a couple of weeks after i posted the sand bath video. it is a shame because there are alot of people that follow my channel and it left a big hole in the process chain.


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## lysdexic

Thank you Geo I'm looking forward to watching the videos with sound (My daughter borrowed my earbuds and everyone else in the house is asleep right now).

I was just experimenting with something like this. I have some aluminum alloy plates 1/4" thick and about 8x10" in width and length. I used some steel stands and pieces of fire brick to raise one of the aluminum plates high enough to put a propane torch under it to heat it. It worked fairly well but with boards not being truly flat contact with the heat source wasn't as uniform as it would be with sand and temperature control isn't very precise. I was thinking of making a refractory base that housed a recycled electric heating element and making a copper and aluminum tray to mount above the heat source... I guess I need to test sand out first.

I've been removing all of the MLCCs and flat packs before looking to do a final depopulation. I may still mechanically remove the MLCCs first, is that a waste of time? The Antimony in the solder doesn't effect the functioning of the stannous chloride? 

My brain is old and brittle and absorbing Hoke and the processes discussed here is going to take me all winter. I am just now ready to reread and reread, search and read, take notes read some more, etc, etc. Acquiring E Scrap, disassembling and sorting is all I am ready to actually do right now. It gives me something to do and time to think. When I'm ready to begin recovery and refining I'll have my material all ready to go. If posting about this before being ready to discuss chemistry is a problem, please say so. Thank you.


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## Geo

actually, depopulating boards is the first step when processing Escrap. whether by mechanical means or thermal, you need to have your game plan ready before you start. like many others, i was using a heat gun to depopulate cell boards because while dealing with my own boards i didnt have enough to use a sand bath. it wasnt until i started processing other peoples scrap that i became aware of the need for greater speed. theres only so many you can do in a days time with a heat gun. the sand bath (my particular sand bath) let me do as many as i wanted to or as many as i had in a days time.

an electrical heat source is not enough heat. if you heat the board too slowly, the board has to stay on the heat longer releasing toxic fumes. you want enough heat to melt the solder quickly so you can get the boards on and off the heat as fast as you can.

you mentioned stannous chloride. i would not recommend using solder from electronics to make testing solution. it is too contaminated with all kinds of metals and may throw the test results off.


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## lysdexic

Thank you Geo and sorry to be a pest, I was referring to you mentioning making stannous using tin/antimony solder.



Geo said:


> stannous chloride is actually very cheap to prepare your self.just dissolve a known piece of tin metal in hcl and you have your stannous chloride.i use 95/5 tin/antimony solder and dissolve several grams in 30 ml's hcl at a time.if all the metal dissolves,add a little more metal until no more dissolves.keeping a little metallic tin in your SnCl keeps it active longer.


I'm not always as clear as I think I am. I can't imagine trying to sort MLCC's out from other microscopic SMD's once they are off the board. Do you process them all (resisters, mlcc's etc) together? 

I experienced what you mean about heating too slowly. I tried before my plate came up to temp, it worked once it was hot enough.

Thank you for your time and knowledge.

- Doug


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## Geo

hcl does not dissolve antimony.its left as a black powder after the solder dissolves. antimony does not effect the testing of precious metals. i only collect the largest of the MLCC's as trying to separate the tiny ones doesnt seem to be worth the trouble for me but for someone else, it may be totally worth it.


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## lysdexic

Thank you again Geo. I'm guessing the antimony not dissolving in HCL is something I should have known about. I have very little scrap to work with at the moment and I'll need enough palladium to make a stock(?) solution, so it's onward with the tedious task of mlcc removal first.

If I may comment on the suggestions of using asbestos or a kayowool fabric. The insulation (refractory type nature) properties of such materials would defeat the purpose of the process. That's why they are used to protect from flame and/or extreme heat.

Hopefully I'll get to test your method before the weather shuts me down completely. I'm shutting up now.


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## ahmadbayoumi

Hello Geo,

I read your posts here over and over as I plan to start my 1st attempt to process cell phone PCBs.

It's really helpful .. Thank you very much 

But I have a couple of questions here:

1- Do I need to remove the solder mask 1st with Sodium Hydroxide or HCL bath would be enough ?

2- The 2nd step would be directly go for AP or do I need to go for Nitric bath then AP ?

Thanks in advance


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## steyr223

ahmadbayoumi said:


> Hello Geo,
> 
> 1- Do I need to remove the solder mask 1st with Sodium Hydroxide or HCL bath would be enough ?
> Thanks in advance



From my experiencewwhich is limited 
It takes a while for the hcl to remove the solder mask and i have seen the gold come of with the mask if left in to long



> 2- The 2nd step would be directly go for AP or do I need to go for Nitric bath then AP ?



Anytime you use nitric you would never go straight to AP or you would most likely make AR and dissolve your values

Incinerate after hno3 bath to assure there is no trace of nitric left
Washing is not enough. 

I am just pointing out a couple facts and am in no way telling you this is correct or not as i dont do cell phones

Geo will answer the question or someone will that knows more than i

Hope this helps steyr223 rob


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## ahmadbayoumi

Thanks a lot steyr223 for your reply.

So I think Sodium Hydroxide should be my 1st step to remove the solder mask ..

Now for the Nitric, I think and after what you have mentioned wouldn't be an option because Incineration is also not an option due to the nature of the PCBs (large size).

So now I'm waiting for Geo or anyone that could help me on this.

Thanks again steyr223 and for everyone here in this great forum


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## steyr223

Also there are members here that will tell you they have seen gold dissolved in sodium hydroxide 

Let see if i know geo he will tell you to scratch the board up so the ap can attack. Under the mask

Steyr223 rob


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## Geo

in my experience, cell phone boards are not gold plated under the solder mask. there must be exceptions but not any that i can find. no need to remove the solder mask before AP treatment. the AP, if done correctly by adding an air supply, will work its way under the solder mask as easily as it does the gold plating. if by chance you have a phone board that has gold plating under the solder mask, the AP will lift it off with no problem even under the solder mask. the solder mask will wind up as green flakes mixed in with the gold flakes but will not effect the dissolution of the gold by hcl/CL when that time comes. the green flakes will be filtered out after the gold is dissolved.


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## ahmadbayoumi

Thanks a lot Geo .. great information.

But if it's so for cellphone broads .. what about other breads ?

I mean which broads that would be gold plated ?


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## Geo

it will work the same for any modern (the past decade) board. i have had the (dis)pleasure of working with some old military boards that had gold traces under solder mask that AP would not effect. these boards had some sort of solder mask that even warm sodium hydroxide solution wouldnt dissolve. i had to physically cut around the edges with a blade so the AP could work underneath the solder mask.


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