silver from A/P solutions

shop deals on amazon
Advertise with us
Shop deals on ebay
xelexo
Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
G

golddigger2

Well-known member
Joined
Sep 25, 2009
Messages
104
Hi I have been refining gold with A/P for the last 6-8 months and have recovered an ounce and a half of good gold from fingers. I have also recovered over a kilo of copper from the waste solutions. I know that A/P dissolves most base metals and was just wondering if it is possible to recover silver from the waste solutions as some of the fingers appear to be silver alloy instead of gold.
 
Hi I have been refining gold with A/P for the last 6-8 months and have recovered an ounce and a half of good gold from fingers. I have also recovered over a kilo of copper from the waste solutions. I know that A/P dissolves most base metals and was just wondering if it is possible to recover silver from the waste solutions as some of the fingers appear to be silver alloy instead of gold.
Click to expand...

I'm not a betting man but I would give you 1000 to 1 odds that those fingers are not silver. Every metal except gold and copper is white. Why do you think they are silver, just because they are white? Have you tested them?
 
no i havnt tested them as i said i havnt had anything to do with silver so far only working with gold. I have managed to get hold of 20 kilos of boards with fingers attached and there appears to be a lot of white metal on them. I assume it could be silver, nickel,tin, or lead im just wondering if silver retrival from A/P is possible even though with what I am refining the silver content would be low to zero. I am just trying to reclaim as much as possible from my solutions before disposal.
 
Chriss, did any of the older stuff have pd plated fingers?
Click to expand...
I never saw any but that doesn't mean they didn't exist. I have heard of Ag/Pd fingers. A couple of large PCB manufacturers in the early 70s used Rh for a few years. I've heard of Pt fingers. A problem with using PGMs is that they tend to polymerize organics from the air and this produces a very thin non-metallic coating on the metal, which could cause connection problems.

Silver isn't used much because it tends to migrate through the board material between the fingers. This can cause partial shorts between the fingers.

http://www.ami.ac.uk/courses/topics/0158_emgr/index.html

All of these metals have been used for fingers at one time or another. However, the odds of your finding them are slim.
 
I used to sell older IBM printers that were coaxial, twinaxial or ASCII. The
printer was always the same but they changed the emulation card to connect
to different mainframe / midrange / RS6000 CPU's. The edge on the cards
we always called "tin" or gold depending on it's color. I always assumed
that the dull grey colored metal on those cards were called "tin" for a reason.
We never called them "silver" or any other PM name. 8)
 
Even newer boards can have palladium. The PCI specification calls for a contact finish of "0.000030 inch minimum gold over 0.000050 inch minimum nickel in the contact area. Alternate finish: gold flash over 0.000040 inch (1 micron) minimum palladium or palladium-nickel over nickel in the contact area."

Given that the use of palladium might have resulted in a lower cost, I would not be surprised to see it used, particularly in low-price, high-volume boards. For anything above low-end boards, I would expect 30 µin of gold as flash does not stand up well to repeated use for even a few cycles, particularly for card-edge connectors. Upon reflection, I would be surprised if gold flash could reliably meet the durability specification of 100 mating cycles without physical damage.

I read that particular line of the specification as applying to both card-edge and motherboard connectors. Another piece of information is that the pins within the plastic PCI connectors on the motherboard are called out as phosphor bronze. They would then be covered with the contact finish detailed above within the contact area.
 
One of the problems with the use of Pt, Pd. or Rh for contacts is that they tend to polymerize organics from the air. If this happens, an organic coating will form on the metal. I have only seen this with rhodium. A company, in the early 70s, was plating rhodium as a final finish on large (maybe, 24"-48" dia.) memory disks. A thin brownish film appeared on the entire rhodium surface after it was sitting around for awhile. Under the scope, it looked and reacted to a probe like rubber cement. Check near the end of the article - frictional polymer.

http://www.brushwellman.com/WorkArea/downloadasset.aspx?id=400

I don't think gold's dead yet. In the 60s, early 70s, I was Senior Chemist for a company that made and sold around 100-150 different gold plating formulations and a few Ag, Rh, Pt, or Pd solutions - this company was the biggest in the world at that time. These solutions would fit all possible needs. With Pd solutions, you only have 2 or 3 choices. The gold baths are work horses - the Pd baths aren't. Probably, 100 times more hours have been spent on Au bath research than on Pd. As a result, Pd baths are behind the times. There's more flexibility with gold and the gold solutions are easier to operate. I would bet that you pay a higher percentage above spot for palladium plating salts than you do for gold. At the present, what is your estimate of the percentage of new boards that use Pd? 1%? 2%?

Also, about the only thing new in precious metals plating over the last 40-50 years has been some very inferior non-cyanide Au and Ag formulations. Pd has always been a lot cheaper than gold, except for about 5 minutes a few years ago. Gold has never been cheap enough to waste. Back then, they knew essentially everything they know now about the possibility of using Pd on PCBs. Why didn't they go to Pd then? Because, it's not as good as gold.

However, for the cheap stuff, you may be right. We've both seen things used that are worse than Pd. I bet the Pd won't be 40 millionths on the cheap stuff, though.

If I had some Pd and some D2O, I might play around with cold fusion.

Chris
 
Yeah, there is nothing like gold for contacts. I certainly don't think it is dead, not even close. I know of nothing that provides similar characteristics. However, people will, of course, continue to try to save money by using less of it.

Percentage of card-edge boards that use gold flash over Pd? Probably very low. I brought it up as only a possibility which should be watched for, not an expected occurrence. Unfortunately, I don't have the experience with low-end, low-cost, high-volume, non-name-brand boards to be able to state a percentage, but I would not be surprised at less than 1%-2%. Such boards would probably just use gold flash over Ni instead of over Pd or Pd-Ni. They are usually not too concerned with meeting regulatory specifications, let alone any non-regulatory specifications (such as the PCI specification). Such boards are designed to work well enough for customers to get out of the 30 day warranty period, but are not intended to be robust. Gold flash will meet electrical specifications on card-edge connectors for only a very limited number of insertion/removal cycles. On the other hand, I would certainly not expect to see anything other than 30 µin gold on any name-brand board where they have to consider reliability as a real cost.

From an industry point of view, both electronics and PM recovery, my main concern about gold flash is the tendency to use gold flash instead of 30 µin of gold. For PM recovery it certainly limits the values that can be obtained from newer material, which makes it less likely for equipment to be recycled rather than being tossed. For the electronics industry, it lowers reliability when thiner platings are used inappropriately.

I was was checking out what other specifications called out for plating thickness and took a side look at the specifications of one manufacturer's HDMI connectors. The majority of them were gold flash over nickel. In fact, I had to read closely and search carefully to find ones from that manufacturer which were 30 µin instead of gold flash. I have a hard time believing, without test results, that gold flash will stand up to the 5,000 or 10,000 (depends on type) connect/disconnect cycles for which those connectors are specified. The HDMI spec. does not specify the thickness of the plating, only the characteristics that the design needs to meet.

On the other hand, I am not too surprised to see a lot of other connectors with less than 30 µin of gold. For instance, on SATA connectors one manufacturer has platings of Gold flash, 5 µin, 15 µin, and 30 µin. The thiner platings on these connectors are a bit more reasonable given that the SATA specification only calls for 50 or 500 connect/disconnect cycles, depending on the use to which the connector will be put. While I have not done an exhaustive search, I would not be surprised to see these plating thicknesses to be normal on SATA connectors. The SATA spec. also does not specify the thickness of the plating, only the characteristics that the design needs to meet.

The vast majority of silver-ish metal that people here will see on card-edge connectors(fingers) from consumer grade equipment will be Sn/Pb solder. If you are lucky it will be Sn/Pb/Ag (a bit more expensive, but a slightly lower melting point, Ag is usually 2%, if present; 3% for some Pb free solders). Solder was, and is, used quite a bit on lower-end RAM to "tin" the leads. It is often much thicker than a "normal" plating and is usually not deposited as a plating process. In general, the force of the motherboard connector on the actual pads is sufficient to break/rub through the oxide/organic layer that formed on the solder. You will normally be able to see an indentation in the tined pads where the connector made contact. Over time these connections can fail, and it is sometimes necessary to re-seat the board/part/etc. There are many formulations for solder. As most people know the industry has been moving away from using Pb for quite some time now. However, it will be in a large portion of e-scrap for quite some time to come.

Cold fusion... well about that...

Dave
 
To test for tin or solder plate, just rub it against a white paper. Tin or solder leaves a gray streak when it rubs off.
Works just as well on pins too.

/Göran
 

Latest posts

Back
Top