# solder behind the boards



## arthur kierski (Jan 31, 2009)

could someone tell me if the solder behind the boards are only tin and lead or they might have in the alloy gold and or silver?


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## goldsilverpro (Jan 31, 2009)

The solder on the back of the board is usually 60/40, Sn/Pb. The leads of the components are stuck through the board and the board is ridden across the crest of a wave of molten solder in a wave solder machine. Then, the leads are trimmed.

If the leads have gold or silver plating on them, some of the gold or silver (also, copper) will dissolve in the solder. At some point, the concentration of these metals will produce poor solder joints and all the solder in the machine will have to be changed. Therefore, it is possible to have traces of Au and Ag in the solder, but it is most likely not worth considering.

With older boards, no intentional Au or Ag will be added to the solder, for these reasons. With very new boards that maybe have eliminated lead, there may be some silver solder used, but I have never heard of it. However, I am not up to date on this matter.


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## arthur kierski (Jan 31, 2009)

gsp, thanks for the reply. your answer became important because with the world crisis , rh plating solutions which was my main product became cheap and even so no one is buying------so i am working with computer boards and as i have a incinerator(a guy who have an incinirator)will incinerate the boards with flatpacks ,pins and copper and solder etc---i will take out only finguers and memories slots and processors - and after incineration i will make powder and extract all the metals from the board---ag ,au, cu,pd,sn,pb--------


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## SilverFox (Jan 31, 2009)

What about the boards that say they are

ROHS compliant?


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## qst42know (Jan 31, 2009)

What they do contain is not specified by the standard. What they must not contain is specified.


http://www.rohscompliancedefinition.com/


Solder manufacturers web sites may reveal content of RoHS compliant solder alloys.


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## arthur kierski (Jan 31, 2009)

the incinirator have all the licenses required to do his work from the brazillian governement---the boards that will be incinirated each month=10000lbs are these


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## goldsilverpro (Jan 31, 2009)

From what I could find on the internet, the lead free solder is tin plus 1 or more of Ag, Bi, Cu, or Ni. I found SnAgCu, SnCu, and SnNi formulations. One manufacturer emphasized that there was no Ag or Bi in their product, as though this was good.


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## arthur kierski (Jan 31, 2009)

thanks again for the interest---after making the powder after incineration,i will abuse of you again asking how would you refine the powder to obtain first the pms-?---------


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## goldsilverpro (Jan 31, 2009)

When you incinerate boards to a white or light gray ash, you end up with a lot of chunks of ash mixed with a lot of pieces of metal. 

The standard way of handling this incinerated material is to first grind it in a ball mill. Then, screen it with an 8 to 10 mesh screen - the metal stays on top of the screen. The metal is melted into bars and the bars are drilled and assayed. If the metal contains a lot of nickel and iron, scrap copper is added to the melt to reduce the melting point so it can be melted in the gas furnace. The minimum copper content in the bars should run about 65 - 70%. The powder that goes through the screen (pulps), which also contains PMs, is blended, sampled with a thief sampler (a metal tube), and assayed. Then, the pulps and metal bars are sent to a primary refiner. The refiner pays for all PMs and the copper. 

This is, by far, the best and cheapest way to handle your material. Also, the material sent to the refiner is easily sampled before shipping. You know exactly its value. If you chose a large world renowned primary refiner or copper smelter, you will get a very honest return. However, they have minimums. You may have to accumulate material for a few months to meet this requirement.

If you plan on processing the incinerated material yourself, I think you will be sadly disappointed. I would *never, never* consider it. What a mess you will have. The costs and labor and waste will be huge and the returns will be small. You might prove me wrong, but don't bet on it.


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## arthur kierski (Jan 31, 2009)

here we have unicore(degussa before being bought) but many years ago i worked with them with autocatalist and i think that i was sucked by them---here we have very skilful men who works with cianide and i am going to give a try with them-as i wrote above, before i do all the incineration and pulverizing i already took it out all processors,finguers and memories and processed them---ps. here in brazil we do not have cianide restrictions(like mexico and colombia)


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## Harold_V (Feb 1, 2009)

goldsilverpro said:


> If you plan on processing the incinerated material yourself, I think you will be sadly disappointed. I would *never, never* consider it. What a mess you will have. The costs and labor and waste will be huge and the returns will be small. You might prove me wrong, but don't bet on it.



I agree.

Harold


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## EDI Refining (Feb 1, 2009)

10,000 lbs is enough for some NA refineries to accept. Let them do the work. 

Or sell the boards as is to a processor

If you need contact of a processor in south america, send me a PM


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## arthur kierski (Feb 1, 2009)

peter,thanks,i am sending a pm to you


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## jamthe3 (Feb 1, 2009)

There was a post last september or so when a guy sent a hair over 10k lbs of boards to a refiner and posted his invoice and their assessment & amount paid. It was back when copper was about $3/lb though so you'd have to adjust the figures & I believe he left all the "goodies" on the boards; ie, chips, memory, etc.

Cheers,
John


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## arthur kierski (Feb 1, 2009)

i read it to ---the refinery was xstrata and one of the results was a yeald of 37,75ounces of gold---thanks for the remenbering---today $35000


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