a lot of this stuff!!

[joheleh]

hi guys, recently a friend of mine gave me a lot of those pcb's (10-15kg)...they're all depopulated, just plastic base and...i don't know, is that gold? may i test them with nitric acid (70%) to see if it's all gold?
My idea was to treat them with HCl(33%) and peroxide(6%)
what do you think about all this stuff?

 

[goldsilverpro]

Looks like gold to me. Probably runs between ten cents and forty cents per square inch of gold plated area.

 

[samuel-a]

Very nice joheleh,

AP is certainly the way to go with those blanks.
Since there's no components, you'll have to find a way to keep them separated for the acid to work all over the surface.

 

[joheleh]

3 more pics

Very nice joheleh,

AP is certainly the way to go with those blanks.
Since there's no components, you'll have to find a way to keep them separated for the acid to work all over the surface.

thanks!! I hope to find a way to keep them separated, but it's a real problem. i have no ideas :roll:

 

[patnor1011]

Get some plastic forks from take away restaurants. Fit about 3 boards in each, you can break handle away.

 

[joheleh]

Get some plastic forks from take away restaurants. Fit about 3 boards in each, you can break handle away.

Nice! I'll try that. I was thinking about the ratio of HCl and peroxide (6%) .... 1:1 seem good to me.

 

[artart47]

Hi !
I've stacked it up in a pile on the table with mixed-drink straws between each. then I'd pick up the entire stack, sqeeze it together and pack them into the inner bucket, ( the one with the drain holes like in Lazersteve's acid peroxide video)
If there is not enough to fill the whole bucket, pouring glass marbles in the voids will keep everything packed together. I washed the marbles with HCl because I diden't know if they were clean .
Hope it helps! Good luck! artart47

 

[joheleh]

Hi !
I've stacked it up in a pile on the table with mixed-drink straws between each. then I'd pick up the entire stack, sqeeze it together and pack them into the inner bucket, ( the one with the drain holes like in Lazersteve's acid peroxide video)
If there is not enough to fill the whole bucket, pouring glass marbles in the voids will keep everything packed together. I washed the marbles with HCl because I diden't know if they were clean .
Hope it helps! Good luck! artart47

Thank you so much, this method seems very efficent, i'll try it soon. What ratio of AP have u used? 1:1? 1:2? (i've got HCl 33% and peroxide 3,6% 12vol)

 

[goldenchild]

You run any of these in hot sodium hydroxide? There may be more gold in the traces under the plastic.

 

[joheleh]

You run any of these in hot sodium hydroxide? There may be more gold in the traces under the plastic.

unfortunately i don't know how to do it properly, i'll work them just with AP...but, if someone can post me a link with some info's it's a little difficult for me to understand perfectly the forum, my english is scolastic...now call me dumb XD

 

[pattt]

Hi johele,

Just my thought (as a newby), AP is the way to go, Hot sodium hydroxide ( caustic soda ) is very dangerous if not handled with very much care, one drop in the eye and you will be loosing that eye :!:
Do a search for it here on the forum.
The gold you see will come off in AP, the gold under the "plastic' coating (if any) will stay on, and if you wish you can do that later, but like i said, be careful !
The peroxide normally used is 3%, if the % is to high it could dissolve the gold.
I'am sure someone will get you more info.

also, study much more , after reading some of your posts, I am sure you need more reading :!:
btw: nice boards.(good starting material)

Have fun and stay safe.

Pat

 

[chlaurite]

Wow, really beautiful! :mrgreen:

Where do people get things like that? I mean, I used to work at a company that made their own boards, and although we had tons of waste/scrap around (wow but I wish I knew then what I know now!), I never saw anything even remotely like that disposed of. Most of the waste I saw came from proto boards or, when actually from the manufacturing floor, bad runs through the wave soldering machine (aka "completely covered in solder). Certainly not never-used blanks like you have here.

 

[joheleh]

Hi johele,

Just my thought (as a newby), AP is the way to go, Hot sodium hydroxide ( caustic soda ) is very dangerous if not handled with very much care, one drop in the eye and you will be loosing that eye :!:
Do a search for it here on the forum.
The gold you see will come off in AP, the gold under the "plastic' coating (if any) will stay on, and if you wish you can do that later, but like i said, be careful !
The peroxide normally used is 3%, if the % is to high it could dissolve the gold.
I'am sure someone will get you more info.

also, study much more , after reading some of your posts, I am sure you need more reading :!:
btw: nice boards.(good starting material)

Have fun and stay safe.

Pat

you're right Pat, i preferred to try my refining experiments with this batch now, because i'm not expert as you in this wonderful forum, i've to learn and to read a lot, AP method seems very user firendly to me, without annoying base metals like in plated pins, connectors etc etc.

i wish (again) to thank you all for your answers, your expertise and knowledge.

Wow, really beautiful! :mrgreen:

Where do people get things like that? I mean, I used to work at a company that made their own boards, and although we had tons of waste/scrap around (wow but I wish I knew then what I know now!), I never saw anything even remotely like that disposed of. Most of the waste I saw came from proto boards or, when actually from the manufacturing floor, bad runs through the wave soldering machine (aka "completely covered in solder). Certainly not never-used blanks like you have here.

chlaurite, this friend of mine works for an import-export society, they're chinese. he gave me that stuff because it was out conformity...for me it's a good fortune i've got those blanks...i know i'm a noob with a "pro" batch...i don't wanna mess up everything

 

[kkmonte]

You don't want to use a 1:1 ratio of HCl and 3% H2O2, that is way too much. Even a 2:1 is too much (iirc). I think Laser Steve's recommendation was 3:1 (3 parts HCl to 1 part 3% H2O2). You just need the oxidizer (H2O2 in this case) to get the reaction going, it will start turning green as it dissolves the copper. As Pat said, too much (or too strong) of an oxidizer and it could dissolve some gold. Once the AP reaction gets going, if you keep it clean you can use it over and over again. Just watch what metals you dissolve in it, if you can just dissolve copper it will last a long time (and slowly grow in volume). You want a nice lighter emerald green color.

If it starts to get too dark green, you need a little more oxygen. If you can get an aquarium bubbler, run the tube and bubble air into the liquid. This will keep the reaction going (and also speed things up a little bit especially in cold weather).

If you start to see white powder forming, you need to add some HCl.

-Ken

 

[everydayisalesson]

Hey jo, an idea came to mind. how about hair combs to keep them separate? You can get like a pack of 20 at the dollar store. Not sure if the plastic is ok, you'll have to ask the guys.

Mike

 

[patnor1011]

Wow, really beautiful! :mrgreen:

Where do people get things like that? I mean, I used to work at a company that made their own boards, and although we had tons of waste/scrap around (wow but I wish I knew then what I know now!), I never saw anything even remotely like that disposed of. Most of the waste I saw came from proto boards or, when actually from the manufacturing floor, bad runs through the wave soldering machine (aka "completely covered in solder). Certainly not never-used blanks like you have here.

Well, I got about bucket full of round boards from smoke detector. I presumed smoke detector is there to save life so there might be more gold on them. They sure looked very nice and promising. While I do not have numbers I remember that yield was so poor that I decided not to get more of that stuff. If I come by some free ones I will do them but I would not pay anything for them.

 

[Anonymous]

Just a word of caution.

Don't get too excited just yet. I had a 500Kg batch of these in the UK that turned out to be pre engineering units. What I thought was plating was in fact a dusting!

 

[goldenchild]

The sodium hydroxide isn't used in place of the AP process but rather to remove the masking of the traces on those boards. You would only have to process one of each type of board you have to confirm that you do or dont have gold under the masking.

LaserSteve's site

http://www.goldrecovery.us/goldrecovery/videos/ShowVideo.aspx?id=soldermask&yt=0

 

[Anonymous]

Scratching the boards with a screwdriver will tell you a lot faster than soaking them.

 

[goldenchild]

Scratching the boards with a screwdriver will tell you a lot faster than soaking them.

True but what if there is gold in some areas and not others? Also, if the plating is very thin you might take that off revealing only the copper underneath. Either way the O.P. has to decide how to proceed.