Gold wires were used for bonding in integrated circuits too. I think because gold is much more ductile, so you can make thin wires that won't break. It's also more resistant to corrosion, which is a problem with copper wire.

The fact that it is more ductile probably also helps with the welding process.

Doesn't copper interact badly with silicon?

I don't know about copper-silicon interactions, but normally you'd bond to a metal pad, not to silicon directly. For a while, the "purple plague" was a problem when gold bond wires reacted badly with aluminum bond pads, forming a purple compound. https://en.wikipedia.org/wiki/Gold%E2%80%93aluminium_interme...

A lot of high performance chips like hybrids (the chip, not cars) are gold bonded. Mainly because its a good conductor and super inert (metal behave funny in contact in space, oxygen is earth's "memory" after all).

> oxygen is earth's "memory" after all

Could you explain what you mean by this?

They may be referring to ‘cold welding’. Oxygen lets metals ‘remember’ what they are connected to. References:

- https://en.wikipedia.org/wiki/Cold_welding

- https://youtube.com/watch?v=Y2nQ8isf55s