There are at least four reasons why all Apple products' circuit boards are black:

1. Heat dissipation: Black solder mask is better than any other colors. There is a wrong idea:Black objects absorb heat better. In fact, from the theory of thermal radiation, heat dissipation and heat absorption are the same;

2. Design style: Even if we know, with the black solder mask covering, from the surface we can’t observe any wiring structure of the circuit. But it’s just a style of designers;

3. Manufacturer's confidence: The use of black PCB definitely reflects a kind of confidence of manufacturer in its products, as well as its prudent workmanship;

4. High-end series simbol: The reason why the high-end series only use black PCB is that a brand has confidence in RD design and later maintenance team.