What the heck is this?

These are really funky looking boards.I believe they came out of an outdated courthouse computer.Ok heres the deal,as far as I can tell the fingers are solid gold,not plated.And all of the tracings are gold with a really thick silver looking plating on top.But whats funny is the gold underneath the tracings really doesn't quite look gold,but it doesnt look copper either.Please help. Well I cant get the pixels low enough to post the picture so please do your best to guess.Or if anyone can help with my camera problems please let me know.

Add the photo as an attachment to your post. :arrow: Add attachment located at the bottom of the post a reply screen.

Here are his pictures: (big pics, go to the link)

pic1

pic2

Sorry, can't upload the third one, too large.

Good luck !

Hi mariannalice,
By the looks of those driver transistors, I'd say the boards are not from a computer but much more likely from a printer.

Also something else here just doesn't make sense. No board manufacturer would cover up gold with tin plating. It may not look like it to you, but I think the traces must be copper underneath the tin. Since we can't see the edge fingers in the photos here, I can't say too much on those. However it is really unlikely they'd be solid gold in any case. They likely have a copper base underneath a thin plating of gold.

Without getting into a photo tutorial, I would just mention that digital cameras generally have a setting that allows you to change the picture resolution. By starting off with a lower resolution picture you don't need to do as much cropping or downsampling to get it to a size that can be uploaded. A side benefit is that with the same amount of memory your camera can hold more pictures if they're at a lower resolution.

macfixer01

Guys I can not thank you enough for the help.Ok now that the pics are on, these boards are 6"x9" and everywhere you see what looks like silver has gold underneath.But nothing under the gold.I have heard of very old platinum boards and wondered if these were some.Also I found about 10 more.And as far as the camera,I set the pixels as low as the camera will allow but its still too high.Think I'll get a different camera soon.Oh yeh,has anyone done any further testing refining the platinum from the HD platters.I processed one down to the foil and liked the result but still need to refine it.Oh and can anyone tell me in detail how to make nitric.I read steves formula but didnt quite understand it.I cant thank you guys enough for all the help and info and friendship.If I can help anyone I will try.
Johnny in Cocoa

Could you not test it with nitric acid. pull a trace loose from the board. If its copper you will know from the sudden green blue bubbling action. Test the silver to.

mariannalice said:

Guys I can not thank you enough for the help.Ok now that the pics are on, these boards are 6"x9" and everywhere you see what looks like silver has gold underneath.But nothing under the gold.I have heard of very old platinum boards and wondered if these were some.Also I found about 10 more.And as far as the camera,I set the pixels as low as the camera will allow but its still too high.Think I'll get a different camera soon.Oh yeh,has anyone done any further testing refining the platinum from the HD platters.I processed one down to the foil and liked the result but still need to refine it.Oh and can anyone tell me in detail how to make nitric.I read steves formula but didnt quite understand it.I cant thank you guys enough for all the help and info and friendship.If I can help anyone I will try.
Johnny in Cocoa

Click to expand...

Johnny,
I can't dispute what you're saying without seeing the boards or better photos. All I'm saying is that it just doesn't make sense to me to put tin over gold, and I doubt even more that it would be platinum. It looks like an ordinary circuit board, possibly from a printer, with tin plating over the copper traces. How are you determining that the traces are gold underneath? Have you dissolved any of it in Aqua Regia or HCL:Chlorox then tested with stannous chloride solution? If you peel copper traces off a circuit board the back side of the traces (seen through the adhesive) often appear a dull golden color. If you scrape through the surface then you should see the pink copper underneath.

Regarding the photos... Setting your camera to the lowest resolution isn't enough. You need software which will let you for example reduce a photo to 25 percent size, or reduce it proportionally given a number of pixels for one dimension or the other. Often there is some limited feature software that comes with the camera. There is also a tutorial in the Useful Tutorials section here that links to a free program you can download (IrfanView) for resizing.

macfixer01

Register at photo bucket.com . They have a built in img resizing program.

Free of course. :wink:

Hi Mac,
I am not positive that it IS in fact gold.But I have stripped hundreds and hundreds of almost every board you can imagine and this doesnt look like any copper ive ever seen.The only way I could imagine that its not gold is if it were brass,and thats a no brainer.I don't know what else to say but I do not have any nitric(thats why I wanted the formula to make it) but I will try to put it in a bath or something to find some kind of result.But I guarantee this is nothing like ive seen b4.
Johnny in Cocoa

Johnny,

You don't need nitric to dissolve copper or tin. HCl and peroxide will do. Just put a four drops of HCl and 2 drops of Peroxide on the exposed trace in 10 minutes or so you'll see the liquid turn blue green color if it's copper (which I think it is). Dipping a cotton swab in the liquid helps show the color change better.

I doubt the fingers are solid gold. Gold is very soft and hence not a good choice for finger substrates. The tinning on the traces can be tested the same way as the copper traces. If the coating dissolves in AP it's not platinum.


The nitric acid formula explains the process in a step by step manner. If you have trouble with it just post a reply on that thread and I'll help you out.

Steve

Good call steve.I had posted that reply in response to the nitric testing, but didnt think about just eliminating the possibility of it being copper and tin first.I will try that today.At least if it dissolves with the AP then I know theres nothing good.And I apologize again but can you please explain to me in very basic terms how to make nitric acid.I have sulphuric(38% and concentrated) acid,muriatic acid,clorox and 3% peroxide.And I have dry sodium hydroxide.I was able to find the sodium metabisulfite after our conversation the other day,but unfortunatley it is in the product "stump out".I dont know how pure it is but It "drops" something out of the auric chloride very well.How pure it is,well thats another story.
Thanks again,
Johnny in Cocoa

Johnny said:

At least if it dissolves with the AP then I know theres nothing good.

Click to expand...

Not true, AP will actually dissolve gold. The AP will only turn blue-green if copper or some other base metal is present. If your AP dissolves some gold just drop it with SMB.

Steve

I just processed some boards like those. Very little gold, but a whole lot of copper.
Anyone have an idea what might be the surface mounts like the one in the middle of the first pic? I have a whole lot more like them on my older boards.

Chuck

Chuck,

The component with the stripes is a common carbon film resistor, it's not considered a surface mount device because the leads go thru the pc board.

Steve

Ladies and gentlemen, at some point SnBi was considered a viable alternative to Au plating. Copper that you see underlying is not pure, but rather alloy, hence the different appeal. It would seem that pictured is a Cu traces board with SnBi or Ag plating, IMHO.

Welcome to the forum,

Not sure what you mean by all this but here's the RoHS compliance comparison on the tin-bismuth you mentioned:
Sn-Bi


Melting point may the best method to identify the various 'silver colored' coatings/solders.

Lead-free Solder Alloys

Steve

Silver plating, when used on traces, has a tendency to migrate through the board material, under certain conditions, thus creating dendrite silver shorts between the traces. For this reason, you will rarely see silver plated traces, or fingers, for that matter.

In 40 years, I have never seen silver plating on traces or fingers.

I also was fooled by the same silvery plate appearance on the tracings years ago. I still have many of these boards. I put one in a electro- cell and tried to find out what metals were present. After I had a mess on the bottom and a black residue on the cathode, I collected everything and analyzed it chemically. All I found was tin, copper, lead, some iron. No Pd or Pt. Bummer. ------ Al :roll: