Hi, i always curious about what kinds of circuit/ technology is that. In some simple analog circuit boards and in some old video game card(eg. NES,SNES game card) there's a circuit that's sealed with a black round plastic kind of thing. What is that?
Manufacturers can save money by buying a bare IC (without a case). They actually wire the chip directly to the PCB skipping the IC package leads altogether. The wires they use are very fine and most chips show some shift if exposed to light, therefore the black coating.