HI,

After reading several topics in the filed, yet I do not know which one is the better conductor for the electricity?

 

Silver is, but often corrodes, if corrosion is a problem then gold is a good choice, but expensive. So most use a copper of some sort.

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Thanks,

I have heard that the silver is the first conductor, the copper is the second and gold is the third.
why they do not use copper instead?

 

They do use copper - it's EXTREMELY rare to use gold or silver, it's just too expensive.

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Best conductors in sequence:
1: Silver,
2: Copper,
3: Gold,
While gold is third why they use it? they can use use copper for ever, why they tend to gold too? Is that due to this fact that maybe copper corrodes too?

 

Yes, copper oxidizes as does silver. Gold does not oxidize as easily as the other two elements.

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Corrosion resistance in sequence:
1. Gold
2. Silver
3. Copper

Cost in sequence:
1. Gold
2. Silver
3. Copper

Three different factors that must be weighed in setecting the right conductor for a particular application.

ken

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And if you look on a periodic chart of elements, you might notice a trend.

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Because of its expense, gold is usually only used as a very thin plating on other conductors, such as copper, to prevent corrosion and provide a low contact resistance. The oxides of copper of and silver are non-conductive.

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Carl
Curmudgeon Elektroniker

 

As said above, silver is the best conductor and good BNC connectors have a silver coating. Silver does oxidize, however the black silver oxide is also a conductor. Ag2O.

References:
GBPPR Tech Bulletin #3 - Why Silver Plate RF Components?
and
Product Review

That said, I have had more intermittent old BNC connectors made with silver than with stainless steel.
Gold connectors are for suckers who buy low oxygen copper cables. However there is a demand for gold connectors and the smart money will satisfy, and profit from, the demand. .....and they won't call their customers "suckers" in front of their faces. That way, everyone is happy.

Bob

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I've always heard that gold is a better conductor than silver. Then comes copper.

 

I guess you learn something new every day, huh? It's easy to find out the truth in Google for technical references or Wikipedia too. You mixed up "conductivity" with "cost of".

Bob

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Sure do. I'll have to use those resources more often.

 

Good quality IC sockets, low level switch contacts and relay contacts are gold plated for excellent reliability. They do not cost more than ordinary silver plated contacts used at higher currents. They are used for switching low level microphones.

My Yamaha stereo has a function switch with silver contacts instead of gold and it is becoming intermittent.

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Uncle $crooge

 

Although silver oxide is a conductor, it's not a good one. And the fact that having silver and silver oxide touching each other creates a bi-metal connection which will start injecting noise into the system like a thermocouple. This is the main reason gold plating is used as it corrodes VERY slowly.