Conductor of Electricity

[Califox]

Which element is the best conductor of electricity?

[theprof]

Silver

[Catso]

Knowing the general accuracy of your replies, theprof, I'm sure you're right, but I would have suggested gold, as it is used in electronics so often. How does gold's conductivity compare with silver's? And why is so much use made of gold?

[theprof]

Yes, you�re right Catso that Gold is also a good contender when it comes down to electrical conductivity.

The top three elements for conducting electricity are firstly, Silver, secondly Copper and thirdly, Gold. I've just referred to Greenwood and Earnshaw for the figures concerned. The book quotes the electrical resistivity of the three metals (in microohm cm) as 1.59 for Silver, 1.67 for Copper and 2.35 for Gold.

Leaving Copper aside, there are a number of reasons why Gold and Silver are used in electronics and more reasons why Silver is the preferred choice.

Both Silver and Gold are malleable and ductile with Gold being more so than Silver. Because of its softness, Gold is little used for structural purposes alone and is often alloyed with Silver or Copper for added strength. However, Gold is great for use in plated edge connectors on printed circuit boards, in mobile phones, in internal semiconductor wiring, and in nanoelectronics where the mechanical demands are at a minimum. The fact that Gold is inert and also unaffected by air are other features in its favour.

The reasons why Gold use is not more widespread is simple � the cost is prohibitive and it is not as conductive as Silver or Copper.

(continued)

[theprof]

Silver has a lot more going for it. Silver is not an active metal and no other element exceeds its electrical and thermal conductivity. It�s only slightly harder than Gold but in practice, this gives it much greater mechanical strength � it too can be alloyed if greater strength is required.

Silver is inert and is used in the food and pharmaceutical industries because it is unaffected by organic acids. It is also used in the electronics industry on printed circuit boards. Colloidal Silver with adhesive mixtures are often used to repair PCB tracks. As far as electronics goes, Silver is the preferred choice due to this unsurpassable conductivity. However, it is also considerably cheaper than Gold, which is another good reason why it�s the preferred choice.

I think it would be fair to say that although much use is made of Gold, Silver use may well exceed it.

[mibn2cweus]

I agree completely with theprof but I would like to emphasize an application where gold has an advantage despite having a bit less conductivity than silver.

Although silver is intrinsically a better conductor than gold, silver acquires a thin layer of oxidation with atmospheric exposure. This is not usually a problem for higher voltage connections where the voltage will "punch through" the thin layer of oxides created from exposure to air but where low voltages are concerned the impervious nature of gold to corrosion makes it a superior electrical contact material, especially when gold to gold mating surfaces are employed.

sorry 'bout the long sentences

[theprof]

That's very valid additional information mibn2cweus.

Incidentally, I don't think you're being the the slightest sesquipedalian or pleonastic at all!