Why is gold used in electronic products as a conductor instead of
silver? I believe silver is the better conductor of the two metals,
but sometimes they seem to use gold instead of silver. Could this be
because the electricity passes on the surface of the metal and
silver's surface is more easily tarnished than that of gold which
doesn't tarnish? (The tarnished silver surface doesn't conduct as well
as gold.)

Hi dawnlinton:


The use of gold over silver in certain electronics is a matter of
longevity weighed against material cost and intended use.


The Gold Institute ( http://www.goldinstitute.org/uses/electron.html )
puts it this way:

"Gold is essential in computer circuitry because of its electrical
conductivity and because it does not degrade over time."

But it's a little more complicated than that.

As you already noted, silver is a better conductor of electricity.
The sigma of silver (electrical conductivity ratio) is  63010000
/ohm.m
(http://www.allmeasures.com/Formulae/static/formulae/electrical_conductivity/29.htm)
 compared to gold's sigma of 45210000 /ohm.m
(http://www.allmeasures.com/Formulae/static/formulae/electrical_conductivity/16.htm)

Not only is silver a better conductor, according to Deringer Contacts,
a specialist in electrical contacts, silver can conduct higher levels
of current than gold:

"This group of materials exhibits the highest conductivity, both
electrical and thermal. . . Being better conductors, this group is
capable of carrying higher currents."  (
http://www.deringer.com/contacts/materials.html )

But in the end, gold still wins out.  Why?  Because most electronic
circuits do not use very high electrical current.  And even though
gold is more expensive, the low surface area used keeps the cost down.
So in the end gold's resistance to corrosion makes it the more
cost-efficient material to use.


Hope this answers your question!

-actualwolf






Search terms:

Gold circuits
conductivity of silver
conductivity of gold
range of silver conductivity


Sources:

The Gold Institute
http://www.goldinstitute.org

Deringer Contacts
http://www.deringer.com/contacts/materials.html

http://www.allmeasures.com