Now the circuit board contacts are basically gold, but now there is technology to use copper, silver and other metals as gold. That is, a layer of gold is plated on the copper foil, even if there is a small amount.
It is because of gold and precious metals that electronic waste recycling has been spawned (of course, there are also components recycling). Many circuit boards are gold-plated, and some chips contain traces of gold. Gold plating is mainly for antioxidant purposes. However, the gold content of the circuit board or chip is very small, and the gold extraction of the circuit board is to be crushed first, then chemical immersion and then replacement with this similar method. The pollution is very, very bad.
Circuit board contacts are generally made of silver or copper rather than gold.