depopulating cell phone boards

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Geo

Geo

Well-known member
Joined
Mar 1, 2011
Messages
7,070
Location
Decatur,Ala.
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]
 
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]
 
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
 
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
 
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.
 
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.
 
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.
 
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)
 
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
 
tomiyet said:
There is unanswered question and thought in my mind, "What chemical can dissolve the whole cell phone boards at a go"
Click to expand...

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
 
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...
 
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...
Click to expand...

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.
 
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.
 
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.
Click to expand...

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.
 
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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