BURIED CAPACITOR Analysis

摘要

Buried sheet capacitance has been used for some time in sophisticated PCB designs. The ZBC 2000, whose patent is owned by Sanmina Corp., is a familiar example. Conceptually, this product consists of one or more inner layers with a .002" FR-4 core. Each such inner layer forms a sheet capacitor of approximately 500 pf per inch. The original purpose of the technology was to replace the surface bypass capacitors with an internal alternative and thereby provide additional outer layer real estate for routing and active components. Later it was also found that a properly designed buried sheet capacitor is an effective method for containing EMI radiation.