Pcb Power Supply System Of Magnetic Material Coating Applications

Current multilayer printed circuit boards (PCBs) often use entire solid power-return (ground) plane pairs for DC power distribution (a power bus structure). As the operation frequency of digital circuits on the PCB gets higher and higher, its EMC (Electro-Magnetic Compatibility) problems have become more important and can no longer be ignored. In fact, the power-return plane pairs in PCBs must be considered as a parallel-plate waveguide system.Using a fast algorithm, based on the cavity-mode model, developed for efficiently and accurately calculating the impedance of a power bus structure in multilayer PCBs, we have focused on the EMI (Electro-Magnetic Interference) problem from the structure and found that coating magnetic material onto the inner sides of the power-return pair planes in multilayer PCBs can increase the surface impedance, thereby contributes to the resonance damping of the power bus impedance, and in further to the improvement of the associated EMC problems. We found out that there is an optimal coating thickness for a given magnetic material to achieve the best resonance damping of the power bus impedance.