Silver mica capacitors provide superior stability and low loss when used in RF power circuits that require low pico farad (pF) and nano farad (nF) ranges. Older silver mica capacitors were manufactured in layers of mica and silver, but the layering allowed room for air gaps that reduced the stability and could also create stress fractures in the assembly.
Modern manufacturing uses silver plated to mica layers, eliminating the gaps. When the desired number of layers is obtained, the assembly is coated in an epoxy or ceramic resin. The coating reduces fracturing of the layers and seals the assembly from moisture and particles that could interfere with the capacitance value.
Mica capacitors are useful in circuits for ripple filtering and are often found in time constant, coupling or resonance circuits. In addition to radio circuits, they are used in TV transmitters and Cable TV amplification circuits. Mica is also a superior choice in high-voltage inversion and power conversion for energy absorbing snubber applications with capacitances of up to 10 nF.