# "silver bearing" solder...



## AuMINIMayhem (Aug 14, 2008)

I just got my hands on BOXES and BOXES of "silver bearing" solder (the wire type, NOT "paste")

Any way to recover the silver out of it? I'm assuming there's lead and tin as well.. unfortunately there's varying solder grades, some are higher than others so I've got to go through a couple hundred rolls and sort them out by grade :roll: 

help?.. anyone?...  

Derek


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## lazersteve (Aug 14, 2008)

Derek,

A main consideration will have to be the percentages of each metal in the alloy. If the tin and or lead content is not high enough they may be passivated (protected) and not dissolved. In this case you would need to inquart with another HCl soluble base metal (like zinc).

HCl will dissolve the tin. 

For lead AR will dissolve it and convert the silver to silver chloride.

Citric acid may also allow you to dissolve the lead and leave the silver intact. 

Maybe someone else will have a better idea.

Steve


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## goldsilverpro (Aug 14, 2008)

Can you estimate the total weight? Are there labels on it. Usually, it gives the Ag content of the label. What is the range of the silver content? 

Silver solder can run from a few percent silver to, maybe, 95% silver. There could be lead, tin, and/or cadmium in it. With Cd in it, it would really be dangerous to melt. 

I would forget about dissolving it, unless the silver is about 30% or more. Dissolving tin would be a mess if nitric is used. 

If there's no Cd in it, it could be melted and the silver could be separated with zinc (Parkes process) or aluminum (Bureau of Mines process).

If the silver content is less than about 25%?, you may be able to selectively dissolve and plate out the Pb/Sn, using an alkaline electrolyte. The silver wouldn't dissolve.

You might be able to sell it back to the manufacturer or another silver solder manufacturer. 
http://www.thomasnet.com/products/silver-solder-76270800-1.html

You could sort it and sell it on Ebay. That might be the smartest move.

No matter what you do, I think you should first find out exactly what you have - percent silver and weights. Very important


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## AuMINIMayhem (Aug 15, 2008)

Steve and GSP.. thanks guys.  

The range is 2-6% Ag.. this is all "silver bearing" solder and not "silver solder" the difference being the later is used for "brazing" rather than "soldering". This came from an micro-electronics place that closed up (other scrappers in the area got ahold of all the Au-bearing materials, circuit cards and pins, primarily :evil: , but when I saw this box I was like "MINE!" :lol: )


Also, I know this isn't the correct thread, BUT I have a huge cooler full of the components I took off of probably 100 pounds or more of SIMMS and DIMMS cards over the last year or so.. I didn't just want to throw them away because I figured there may be pgm's there. I bet I have at least 50 pounds of "DIPs" shown in the picture below..I have a dewar filled with liquid Nitrogen and I was thinking of taking these (a small bucket at a time) and shattering them through thermal shock to separate the metal foil inside them.. I cracked a few open and there's a small metal foil (copperish colored on one side and silver-ish on the other) also some foils are "bluish" almost like they were anodized..

Am I wasting my time?


[img:366:309]http://www.webopedia.com/FIG/CHIP.gif[/img]


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## goldsilverpro (Aug 15, 2008)

I would try to sell it, as is. Either on eBay or to someone who can use it. It's worth from about $3.50 to $11/pound in silver. Sounds like you have a lot of it and I think you'll have a big mess and a lot of waste if you try to dissolve it.


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## AuMINIMayhem (Aug 15, 2008)

yeah.. I as leaning towards that myself.. (talking about the solder, right?)

what do you think about the DIP chips though?


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## goldsilverpro (Aug 15, 2008)

I meant solder.

Are the DIPs plastic or ceramic? Black? Either could have value or they could be worthless.

I used to heat up the ceramic ones to, maybe, 800 F and then quench then in water. The glass holding the 2 slabs of ceramic together then shatters and they fall apart. I then tumbled them in a small cement mixer and then pulled out the metal (kovar) with a magnet. The gold on the ceramic can then be removed with AR or whatever. On the ones I worked with, there was no gold on the metal. The kovar has scrap value, since it is 29% Ni and 17% Co.

If they're the plastic type, you're on your own. N2 may be the best way to crack them open. The big guys burn them. By the colors, though, it doesn't sound like gold. If there is gold on the kovar fingers inside, they would be yellow. The chip is attached to the kovar pad either by Au/Si solder (very pale yellow - almost white), silver solder (white or gray), or epoxy.


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## AuMINIMayhem (Aug 15, 2008)

they're ceramic for the most part..

Yeah, I'll do the thermal shock deal, see what happens.. you're saying don't throw away the ceramic tho, treat the ceramic with AR to pull out an Au values right? 

And the metal inside, no platinum/palladium etc plating?.. bummer..


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## goldsilverpro (Aug 15, 2008)

What is the date on these? It would usually be the 1st 2 digits of a 4 digit number on the part, if it's there.

Look for gold on the chip pad on the ceramic. I'm not saying that PGMs are not there. But, the only thing I've ever seen on these parts is gold, silver, or epoxy. Use an eye loupe and check them out. Put a drop of aqua regia on the chip pad on the ceramic , let it work and then test with stannous chloride. Check one for silver with a drop of nitric, let it work, and then test with a drop of HCl.

I have seen ceramic ones that have about a 1/4" spot of gold plated on the tips of the kovar inside fingers. On most, however, the gold is only on the ceramic. If the part were made in the last 15-20 years, it could be a different ball game. The ones I dealt with were at least 15 years old.

Do a bunch of testing before you come to any conclusions. Use your knowledge.


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## AuMINIMayhem (Aug 16, 2008)

right on.. yeah... they're fairly new.. Ive been doing some research and looks like a lot of chips are using an Aluminum alloy, which would totally suck and make it a complete waste of time, I'm going to grab a couple throw them in with some plain old HCl, if it dissolves them, I'll know it's aluminum and not worth the trouble (I just brought 80 some odd pounds to the recycling depot and only got about 60-plus bucks.. and that was good sized machinist quality chunks, some wighing over ten pounds each..)

Also, on a side note, I stopped by the local land-fill.. they have a place where people are allowed to take stuff... an amazing amount of brass items were there (as well as about a two pound sterling serving platter "Dibs!"). Yellow brass is going for about a buck to a buck fifty a pound and there's tons everywhere, old ceiling fans, those tack old chandeliers.. I'm on my way to just sayin screw it, buyin a cheap old truck, getting a business license and starting this as a side job. 

On a side note: I would highly suggest getting a business license and playing "above the board" if anyone is considering doing aluminum, copper, brass, etc... there's a ton of news article out there of guys getting arrested for stealing materials from job sites.. all you need to do is get pulled over with a car load of scrap and you've got probable cause.. just a little note of caution for anyone interested in pursuing regular scrap...

Derek


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