Apple (and most high end tech designers) use highly specialized, very $$$ PCBs for a lot of their products. They aren't created by traditional litho + etch, bu

Apple (and most high end tech designers) use highly specialized, very $$$ PCBs for a lot of their products. They aren't created by traditional litho + etch, but rather by a process called modified semi-additive processing (mSAP). iPhone, apple watch, etc PCBs are basically the same as CPU/IC interposers on a large scale. Definitely not 1 cent/sq cm cheap, but they have massive volume and high price points. It lets them get the insane part density needed these days.