Anyone have a number, in terms of RRR, for the plated copper purity?
TIA.
Anyone have a number, in terms of RRR, for the plated copper purity?
TIA.
I've never even heard of RRR. It appears to be,
Offhand, plated copper is likely to be >99.9%, with oxygen and hydrogen being major impurities (one could guess at metal impurities, like Sn or Pb?). This chart shows the difference per %at impurity, which is NOT in terms of RRR.
Tim
-- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
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99 44/100 percent pure.
No..wait...that's something else...
mike
No idea, could you stick a piece in LN2 and get some measure? (There's a graph for Al in White's Low Temp Phyiscs text... I'm trying to remember where I saw one for copper. Kittel?)
Isn't it likely to change for different sources?
George H.
This has some lower temp values,
Evidently, RRR(Cu) ~ 1.712 / 0.002 = 856, presumably for research purity Cu (>4N???).
Tim
-- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
I'm guessing the number is going to be less than 100. For ordinary drawn copper wire it's apparently about 50, and I don't expect plated copper will be better than that. It gets up into the tens of thousands for really pure metal.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com
Fascinating. Regular copper at room temperature is already pretty conductive. It must be scary at ~absolute zero, especially when very pure (and, I might guess, single crystal as well?).
Heck, even if regular stuff is about 50, that's only 98% of the way to a superconductor. If a bar of copper at STP can hold a magnet with a ~seconds time constant, really cold, pure copper must do a pretty good magnetic levitation trick all its own!
Tim
-- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Copper _never_ goes superconducting, interestingly. Lots of elements do, but not Cu, Au or Ag. Aluminum does weird stuff.
Sort of. As I think of it, a superconductor has infinite conductivity, so you can't get halfway there.
Interesting idea. Skin effect starts to become important at much lower frequencies.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com
Yes, nonzero, not superconducting -- which will generate interesting side effects, like very long L/R time constants, with no Meissner effect.
Well, 98% *from* copper... Obviously, infinite % from zero! :)
That too!
Tim
-- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
I'm guessing the number is going to be less than 100. For ordinary drawn copper wire it's apparently about 50, and I don't expect plated copper will be better than that. It gets up into the tens of thousands for really pure metal.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com
Isn't the copper that wire is drawn from "electrolytic"?
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com
The result depends on the level on contaminants in the copper anode and the electrolyte.
Electrolytic refining can improve the purity by several orders of magnitude, but it is not perfect. A small percentage of contaminants will still pass through the process. However, you can use multiple stages where the purity increases in each stage.
Regards
Mike
ure
conds
I think I saw a plot where really pure aluminum had a resistivity lower than copper at LN2 temperatures. So a neat demo is to drop a magnetic onto a plate of aluminum in a LN2 bath. A nice soft landing!
George H.
ity
=A0"The Journey is the reward"
I just tried it with a really strong magnet and a big copper bus bar at room temperature- a noticably softer landing, but a long way from levitating.
ure
aconds
Oh you can't levitate it. But it's similar to a demo where you drop a magnet down a copper tube. It'd be 'cool' to get the tube at 77K and see the difference. Trying to get an idea of the optimal thickness (skin depth) and rate of change in the B field gives me a brain ache.
(According to the tables in the back of White's book, Al and Cu have about the same resistivity at 77K... so my above statement appears to be wrong.)
George H.
I've used conductivity at 80% of pure and been close to measurements.
Don't know if that is from purity, or porosity.
It is VERY pure.
Cincinnati Milacron made the original machines that 4 x 8 foot sheets of single and double sided PCBs were made from way back in the sixties.
Layers are pretty thin now, but the cladding steps are probably quite similar.
I'd say the purity is very high.
The thing is though... many folks nowadays are using gold boards and copper is no longer a factor to any degree like it was.
The RoHS ushered in platings that will hold up in the high heat environments and still wet well. Copper isn't on the list. At least not in pure form. I'm sure there are plating alloys that get used.
=20
=20
radioactive=20
Not perzactly. Lookup drawn wire to learn why.
?-)
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