As a social scientist I lack much technological understanding, so there is a question on technology and natural sciences that I’m really interested in but could not find a proper answer when searching the web.
What exactly is the function of gold in a smartphone? What are the physical qualities of gold that make it a better solution in comparison to other metals? Could it be replaced (probably at an expense of some kind or another) or is it literally indispensable?
The first two arguments, gold is highly conductive and easily workable when melted, were known to me.
The third argument, gold is resistant to oxidation, is comprehensible but dubious at the same time: Why is a technical application, which is used for two to five years, with a lot of wearing parts – these expandable parts actually limiting the utilisation period – in need of gold as an expensive and highly problematic component with a lower tendency to oxidise? Is it providing connections that would break down when built with another metal?
In other words: Which effect would the replacement of gold with a resource of similar, probably lower but nevertheless comparable qualities have? If the difference is of important: why is it?
I guess, my motivation for asking becomes obvious: gold is expensive and problematic. So what does it actually do, so that it is not replaced with something else?
Part of it is simply that when you ask a chip fab to build you a chip (and these days this is almost always outsourced to one of a few big fabbers: for high-end chips like those usually found in smartphones, one of only two), until quite recently they would use gold for the connections to the pins inside the package simply because that is how it has always been done (and transitioning from gold to copper has timing implications and may require some redesign and/or layout changes). They are moving to copper (and a lot of modern chip packaging uses copper), but it’s not a trivial change and it’s harder to use for these applications than gold is.
besides that good summary from @AnotherElk here another one (cause we all never can learn enough )
This article is mostly written in german (with some english in it) but I recommend to use a translator like deepl.com (or similar) in case you’re not familiar with german
But besides both articles keep in mind:
Gold is not only a key component of smartphone but also a key component of any electronic device (computers, TVs, freezers, bla, bla … almost everything that runs with electricity - except maybe a simple fan )
Manufacturers all around the world want to make money and they want to keep they expenses low.
The fact that no manufacturer ever found a practical way to replace gold in such devices shows that there’s until today no alternative to gold known to replace it.
Manufacturers try hard to keep the amount of gold at a minimum already. But we also can’t live without it.
Gold is the “jack of all trades”-element in electronics
Last but not least: Gold is expensive - but it’s not problematic (just compare it with plutonium - that’s what I call problematic ). We humans make it problematic the way we exploit others & nature to get it.
PS: I’ve found also a good english source giving a great detailed summary why gold is used:
You’ve already covered the physical characteristics of gold that make it indispensable.
Relatively low melting point, high electrical conductance, very malleable, very ductile, very low corrosion,
The reason gold was used as the basis of currency for so long is because it doesn’t change characteristics or corrode with time. That gold has so many uses was reflected in the value it was given in trading.
Copper is better for electrical conductance, but it does suffer from corrosion over time in normal air. That’s why gold is mainly used for the CPU package contacts and the sliding electrical contacts of cables.
One more thing that gold does better than any other metal is reflect heat. It’s why the mirror segments of the James Webb Space Telescope are gold coated. It reflects infrared better than any other metal.