Capacitors in PCB can be formed using special layers made of various dielectric material in a multilayer PCB. Today BC2000 a capacitive laminate from Hadco/Sanmina is the most common.
Products from DuPont, 3M,Shipley and Mitsui Metals are also developed.
The area required to implement a capacitance value in a PCB limits applications to small capacitance values.
Capacitance formula: C=E,*A/t, C =Capacitance E, =Dielectric Constant, A = Area, t = thickness
- Surface mounted discrete capacitors are ineffective above 1 GHz
- Low impedance and high capacitance at high frequencies
- Impedance is more critical than capacitance at high frequencies
- Lowe power bus noise can result in reduced radiated emission