Militoy said:
A few comments -
I work almost daily with gold-plated military connector pins - and have for the past 35 years or so. So I've had quite a bit of exposure to gold-plated pins, and the specifications describing them. I have made a habit over those years to scrounge or to buy at low cost any gold scrap I see being disposed of. Often - that scrap has been free for the taking - as it has been destined for the dumpster, or the e-waste bin - where my employer has to pay for disposal. I've sold quite a good amount to refiners - and now I choose to do the refining myself - just because I can, and it's interesting. I wouldn't totally dismiss the value of the pins until at least after I had done a bit more digging. WB Parts is one of many surplus / discontinued military parts "headhunters" - and I wouldn't take the ".005 grains" as gospel until I had read the actual specification myself. Parts headhunters are notorious for misinterpreting or mis-stating specs. The weight requirement might be accurate - or it might actually be .005 grams. The plating in mil specs is typically specified as a specific alloy and hardness, at a minimum thickness requirement. In the 70's, plating technology wasn't up to today's standards - and gold was fairly cheap compared to the price of a military connector (remember the $300 toilet seat?). I would not be surprised to find that the plating thickness on some pins exceeded the minimum by 2:1; or even 5:1. The bottom line is - do your homework all the way - not everything you read on the internet is accurate. If you are able to source a small sample to process, take careful weight measurements at every step of your refining - and test for gold before you dispose of any waste chemicals. After you have run a test batch, you will be able to determine the actual value of the raw material to you - considering all labor, shipping and chemical costs.
The gold plating thickness for vital areas, such as wear surfaces (pins, fingers, etc.) and parts that must be heated for die attach (IC packages, etc.), was the same then as it is today. What has changed is that many non-vital areas (portion of the pin that does not make contact, e.g.) are plated thinner (using spot or zone plating equipment, e.g.) or not gold plated at all. The plating baths used then are about the same as those used today, with very little advancement in technology. Gold is gold and it has always taken about 30 micro" to protect a wear surface. Gold has never been cheap and any plater that put on 2 to 5 times more gold than was needed would soon go broke, even when gold was at $42. Besides the added gold costs, it would take 2 to 5 times longer to plate and they would only be able to get 1/2 to 1/5 as much production.
A long time ago, in the 30s, 40s, and 50s, a lot of items were plated heavily. For example, we once processed some 40s pins that ran 1 oz/pound. At that time, gold was plated from inferior alkaline cyanide baths and such things as silver or copper were used as an underlayer. They didn't know exactly how much gold thickness was necessary for various applications, so a lot of stuff was overplated (especially during WWII). When the superior acid baths (still used today) were developed in the late 50s, early 60s, and they started using nickel as an underplate, they were able to get a handle on how much was really needed for various applications. Those figures are about the same today.
In certain military applications, such as when the parts will be around salt water, the plating was, and is, much thicker than the norm. This is because all gold plating is porous and the porosity doesn't approach zero until the thickness is greater than about 100 micro". I once got sucked into processing the electronics from a scrapped out Navy submarine, probably made in the 70s. Gold plating was everywhere and I expected it to be thick due to the application. However, it was very thin, difficult to process, and I lost money on it. With military stuff, you never know without a bunch of intelligent sampling and assays. In my experience, it can be all over the map.
To back all this up, let me add that, in the late 60s, early 70s, I was the Senior Chemist for the world's largest supplier of PM plating systems and solutions (Sel-Rex, West coast plant). Also, in the mid 70s, I owned 2 hi-tech gold plating shops, with customers such as Intel and AMD.
Gold has always been valuable and it has never been wasted intentionally. Never!
Chris
, he has another 3 lots on auction i was thinking of buying, i might give them a miss now.
