ザ・ capacitance formed between copper planes in different board layers is typically much smaller than the capacitance from discrete capacitors. but it has a very low parasitic series inductance and therefore is the most important capacitance for frequencies above a few 100 MHz. This frequency range is important for decoupling fast ICs or for handling ESD.
ザ・ capacitance between a trace and the plane underneath is important for transmission line impedance. A thinner dielectric reduces the characteristic impedance at the same dimensions. therefore trace dimensions can be smaller for the same characteristic impedance, which facilitates dense high-speed routing.
続きを読む: 重い銅のPCB
#PCB 設計 #PCB 材料
