need help with info on scrap

[g_axelsson]

Sure! No worries mate, I might be wrong in the end but I don't think so.

Either I'm right or I will learn something new. In both cases I'm winning! :mrgreen:

Göran

 

[nickvc]

Goran with military materials cost is usually of second consideration, they have to work and in various environments so perhaps the Pt was added to strengthen the alloy or thinly plated to protect them, I have seen obscene amounts of gold on military scrap, the highest I remember was 90 grams a kilo but I'm sure we had one batch higher than that, specific applications no doubt and I have no idea what it was for.

 

[anachronism]

As Nick says, and I am sure Goran is aware too, you can pretty much tear up the rule book on "what pm goes where" when you're discussing military, aerospace, and enterprise telecoms equipment. I can remember reading posts on here where people have said that they have never seen gold plate on Aluminium and cannot see the use of it but that's heavily used in telecoms as an example.

Cost isn't an issue. Reliability is. With some telecoms boards costing in excess of £30,000 each the few extra £ of plating thickness, or the replacement of an adequate base metal with a perfect precious metal is the norm.

 

[g_axelsson]

Anachronism sent me an XRF readout showing Pt but the major metals were tin and lead with minor copper. Since he hasn't posted it here I won't mention more details.

After an hour of researching I had only found one mentioning of platinum on circuit boards and in that case it was sputtered on, not plated.

So far I would stake my reputation as an electronic circuit designer that there is no purpose to plate platinum on tinned conductors and it is virtually impossible to remove any platinum between conductors if it was sputtered after the circuit board were etched.
Just think of it, removing a metal that normally takes boiling AR to dissolve, plated on copper conductors. If they have a problem with copper chloride etching under the resist then boiling AR would eat copper as candy floss.

There is a small probability that the board was plated by an electroless immersion bath, not that I have ever heard about one. And then afterwards tin coated (HASL = Hot Air Solder Leveling), then platinum would be dissolved by the solder. Another possibility is that it is a special solder developed to combat tin whiskers that could develop. But 60/40 tin solders seldom have that problem.
Any way, that is not platinum traces, it is platinum containing solder plated traces. Just as some wave soldered boards can have up to 0.5% gold contamination in the solder.

Göran

 

[Johnny5]

I would imagine these are Pt as well. I have a couple of totes of them, but I never got around to testing them.There's a lot of Ag and Pd on them as well.

 

[g_axelsson]

Tin plate... or more probably solder plated. It's called HASL for Hot Air Solder Leveling.

Göran

 

[g_axelsson]

Easy test, heat the surface with a hot air gun, if the surface melts even the slightest before the board is glowing red hot then it was just solder. Use a piece of paper towel to push at the surface to break the oxide layer and to see if it has melted.

Lead-tin solder melts at 180 - 190 °C (360 - 370 °F), copper around 1000 °C and platinum way higher.

Göran

 

[goldsilverpro]

Johnny5,

You're seeing things you wish were there but really aren't there. How were you going to test this stuff for platinum, anyhow? Some people think any white metal they see on electronic materials is platinum or one of the other platinum group metals. The fact is that the only common metallic elements that aren't white or gray are copper and gold and their alloys, like brass. There are many 100s of different white or gray metal elements and alloys. Platinum group metals are all rare and expensive and they're only used on very specific, special, rare applications. No manufacturer in the world is dumb enough to use them where some cheaper metal would work just as well. They're never used on large plane areas like the board covered with tin in one of your photos - never.

Zero platinum on those boards. Some of the only platinum I've seen on a board was paliney alloy wire wipers on very rare types of rotary switches. I also remember IBM boards, from the 70s, that had a bunch of aluminum lidded hybrid circuits with some platinum traces on them. That's about all I can remember that had platinum on them. These are the same boards with a row of spring contacts that had tiny PM contact points on them. They've been discussed a few times on the forum.

I see no palladium. About the only palladium you'll ever see on a board is on some of the tiny chip capacitors.

In the late 60s, early 70s, Zerox plated circuit board fingers with rhodium. Other than that, I can't recall ever seen platinum group plating on a circuit board and I've been doing this stuff for 50 years. Thinking back, though, I did see white gold/palladium alloy plating on reed switches but I only saw that one time.

Except for the tiny amount of Pd on chip capacitors and the occasional hybrid circuit, PGMs on electronics are as rare as hen's teeth.

 

[Johnny5]

Johnny5,

You're seeing things you wish were there but really aren't there. How were you going to test this stuff for platinum, anyhow? Some people think any white metal they see on electronic materials is platinum or one of the other platinum group metals. The fact is that the only common metallic elements that aren't white or gray are copper and gold and their alloys, like brass. There are many 100s of different white or gray metal elements and alloys. Platinum group metals are all rare and expensive and they're only used on very specific, special, rare applications. No manufacturer in the world is dumb enough to use them where some cheaper metal would work just as well. They're never used on large plane areas like the board covered with tin in one of your photos - never.
Zero platinum on those boards. Some of the only platinum I've seen on a board was paliney alloy wire wipers on very rare types of rotary switches. I also remember IBM boards, from the 70s, that had a bunch of aluminum lidded hybrid circuits with some platinum traces on them. That's about all I can remember that had platinum on them. These are the same boards with a row of spring contacts that had tiny PM contact points on them. They've been discussed a few times on the forum.



I see no palladium. About the only palladium you'll ever see on a board is on some of the tiny chip capacitors.

In the late 60s, early 70s, Zerox plated circuit board fingers with rhodium. Other than that, I can't recall ever seen platinum group plating on a circuit board and I've been doing this stuff for 50 years. Thinking back, though, I did see white gold/palladium alloy plating on reed switches but I only saw that one time.

Except for the tiny amount of Pd on chip capacitors and the occasional hybrid circuit, PGMs on electronics are as rare as hen's teeth.

Thank you for the advice, and thank you for the lesson. Hot Hcl would dissolve a tiny piece of that material quickly if it were solder.
As per the Ag and Pd statement, next time I'll be more careful to proofread what I've typed, prior to submitting it. I meant Ag and Ta. It was a simple mistake, one that I will NOT make again.

 

[goldsilverpro]

Also, silver isn't used for traces, fingers, or large plane areas, because of a couple of reasons. It tarnishes and it tends to migrate on the board material, over time. This would be worse if it were used on fingers. There are lots of photos on the internet showing this silver migration effect. With fingers, you would probably, over time, get electrical shorting of adjacent fingers

 

[Johnny5]

Also, silver isn't used for traces, fingers, or large plane areas, because of a couple of reasons. It tarnishes and it tends to migrate on the board material, over time. This would be worse if it were used on fingers. There are lots of photos on the internet showing this silver migration effect. With fingers, you would probably, over time, get electrical shorting of adjacent fingers

While not (normally) used for traces, there are several companies that have used silver in their solder baths. I have about 30 lbs of components that came from a company that had an accident, and as a result had to dispose of 10's of thousands of components, most of which have silver solder on them. While silver is more electrically conductive than gold, due to it oxidizing, and high migration rate, gold is used (in most cases) instead, on top of the nickle barrier of course to keep it from migrating into the initial plate material (usually copper).

 

[g_axelsson]

Actually, silver is used as a surface treatment of circuit boards and as long as the boards is soldered in time it works quite good. It is a cheaper alternative to ENIG coating but with a shorter storage time.
I have specified a couple of circuit boards where we used silver plate as the coating.

Johnny5, asking about tantalum capacitors in a thread discussing PGM plating of circuit boards... why? There must be hundreds of threads about capacitors that are better suited for that discussion. I would also look inside the rectangular yellow capacitors to see if there is a MLCC inside.

Göran

 

[Johnny5]

Johnny5, asking about tantalum capacitors in a thread discussing PGM plating of circuit boards... why?

Göran

I wasn't. The thread was about the possibility of Pt traces. That's what my first comment (and pictures) were based on.

 

[g_axelsson]

I see it now... but you might have been correct the first time writing Pd. You should really check the yellow rectangular capacitors to see if there is a MLCC inside.

Göran

 

[Johnny5]

Thank you Goran, That may very well be true, however when I wrote that, I meant to say Ta. I was not paying attention to any other PM's that may have been present.
I found a buyer for those Ta caps that is not too far from here. I may see if they would be interested in the other stuff.