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Author Topic: Why use gold in electronics, rather than lead?  (Read 13186 times)

sharkeyandgeorge

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Why use gold in electronics, rather than lead?
« on: 28/12/2005 11:37:55 »
the electronics industry uses a lot of gold and platinum in chips and wiring why not lead its almost identical to gold so why dont they use this much cheaper option does the one molecule really make that much of a difference?

"I realised i was sitting on a thousand tons of fuel in a rocket built by the lowest bidder"
« Last Edit: 21/05/2010 17:36:16 by chris »


 

another_someone

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Re: Why use gold in electronics, rather than lead?
« Reply #1 on: 28/12/2005 15:57:27 »
quote:
Originally posted by sharkeyandgeorge

the electronics industry uses a lot of gold and platinum in chips and wiring why not lead its almost identical to gold so why dont they use this much cheaper option does the one molecule really make that much of a difference?

"I realised i was sitting on a thousand tons of fuel in a rocket built by the lowest bidder"



As far as I am aware, the conductivity of lead is nothing like as good as the conductivity of gold.  The other advantage gold has over many other metals such as copper or aluminium is that it does not form an oxide layer on its surface, but this may also be true of lead, and so would not be a distinction there.  But the conductivity of lead I do believe is very much inferior.
 

Offline neilep

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Re: Why use gold in electronics, rather than lead?
« Reply #2 on: 28/12/2005 17:02:51 »
True, Gold is a superior conductor than lead. For accuarate transmission of data (especially from an audio point of view) then gold and other rare earth metals, is the best.


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Offline DoctorBeaver

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Re: Why use gold in electronics, rather than lead?
« Reply #3 on: 28/12/2005 17:26:10 »
Steel & brass are also extensively used
 

another_someone

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Re: Why use gold in electronics, rather than lead?
« Reply #4 on: 28/12/2005 18:55:41 »
quote:
Originally posted by DoctorBeaver

Steel & brass are also extensively used



As I understand it, these metals would not be used in electronic circuits, but in electrical distribution, in areas where the mechanical properties (as well as the cost aspects) of the material is more important than the electrical properties.  You can often make up for poor conductivity by increasing the cross section of the conductor (where space allows), and so using a thicker conductor of a cheaper material may well provide just as good conduction properties as a thinner conductor of a more expensive material.

Again, gold tends only to be used for contacts, where the lack of surface oxidisation makes it particularly useful when compared to copper, which would be the predominant conductor used on printed circuit boards (in any event, gold on printed circuit boards, apart from being expensive, would be difficult to etch because of the relative chemical inertness of the material).

Steel, I would imagine to have particular problems in high frequency circuits because of its magnetic properties.
« Last Edit: 28/12/2005 23:33:11 by another_someone »
 

Offline DoctorBeaver

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Re: Why use gold in electronics, rather than lead?
« Reply #5 on: 29/12/2005 13:10:35 »
quote:
As I understand it, these metals would not be used in electronic circuits


I would class the guidance systems of Rapier missiles, Exocet missiles and Stingray torpedoes as electronic and I know for a fact that brass connectors are used in them
 

sharkeyandgeorge

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Re: Why use gold in electronics, rather than lead?
« Reply #6 on: 29/12/2005 13:59:41 »
ok then the conductivity of leads not so good anyone know why? this may be stupid but i thought the heavier the metal the better conductivity not true?

"I realised i was sitting on a thousand tons of fuel in a rocket built by the lowest bidder"
 

Offline DoctorBeaver

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Re: Why use gold in electronics, rather than lead?
« Reply #7 on: 29/12/2005 14:24:45 »
 

another_someone

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Re: Why use gold in electronics, rather than lead?
« Reply #8 on: 29/12/2005 14:36:01 »
quote:
Originally posted by DoctorBeaver

quote:
As I understand it, these metals would not be used in electronic circuits


I would class the guidance systems of Rapier missiles, Exocet missiles and Stingray torpedoes as electronic and I know for a fact that brass connectors are used in them



I don't know much about the internals of the rapier or exocet, but I would ask whether the brass connectors were used for the signal paths or the power supply to the electronics?

It may also be because of the needs of physical robustness that brass is used in these environments even though in civilian use gold might be the preferred material (or at least copper).
 

Offline DoctorBeaver

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Re: Why use gold in electronics, rather than lead?
« Reply #9 on: 29/12/2005 14:54:44 »
Mainly as connectors onto the PCBs
 

another_someone

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Re: Why use gold in electronics, rather than lead?
« Reply #10 on: 30/12/2005 05:00:01 »
quote:
Originally posted by DoctorBeaver

Mainly as connectors onto the PCBs



But again, are you talking only about power connectors, or both power and signal connectors.

Again, there are questions about the thickness of the connectors, and the frequency of signal the connectors are expected to carry (which is why power connectors would be less sensitive, but even signal connectors, if one did not require a large number of very small pins, might be viable).
 

Offline DoctorBeaver

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Re: Why use gold in electronics, rather than lead?
« Reply #11 on: 30/12/2005 12:18:53 »
The large ones were definitely power connectors but there were smaller, multi-pin connectors too. I'm not really sure what they all did. I was a tester. All I had to do was connect them to a test rig and make sure they worked.
 

Offline Crazy

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Re: Why use gold in electronics, rather than lead?
« Reply #12 on: 21/05/2010 11:20:52 »
I don't know much about lead, but gold is such a good conductor it can be stretched very thin as to connect integrated circuit components to their pins within the substrate,making minituration a reality.
 

Offline djdave

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Re: Why use gold in electronics, rather than lead?
« Reply #13 on: 21/05/2010 11:31:37 »
Gold for the Win.
 

Offline graham.d

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Re: Why use gold in electronics, rather than lead?
« Reply #14 on: 21/05/2010 13:18:30 »
Goodness, this is a very old topic being dragged up from the archives.

Gold is a good conductor, malliable and ductile. And its specific properties can be modified by alloying with other materials. A very importent property is that it is largely immune from many unwanted chemical attacks, particularly oxidation, so it is good for making surface to surface electrical contacts. This resistance to forming chemical bonds is also good in maintaining high reliability in electronic components.

It can, however, form some chemical bonds and has been a source of problems in the past (now largely overcome). A phenomenon called "purple plague" was a serious problem in the semiconductor industry many years ago. This is caused by the formation of various intermetallics from Aluminium and Gold. Aluminium is used as an interconnect on many semiconductor devices and gold is used as the bondwire connection from the chip to the package.
 

Offline Bored chemist

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Why use gold in electronics, rather than lead?
« Reply #15 on: 22/05/2010 01:17:08 »
I see that "Crazy is a newcomer to this site.
Hi Crazy.
You might want to look at the dates on posts before you reply to them
 

Offline tommya300

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Why use gold in electronics, rather than lead?
« Reply #16 on: 23/05/2010 00:37:24 »
I see that "Crazy is a newcomer to this site.
Hi Crazy.

You might want to look at the dates on posts before you reply to them

Wow got my attention. Where is the Housekeeper?  



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Why use gold in electronics, rather than lead?
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