Development of high accuracy standard capacitors

This paper describes the dielectric material and the structure of standard capacitors developed by NIM, with capacitance range of 1pF to 1μF and the accuracy of 5ppm to 50ppm at 1 kHz. High stability and high accuracy of standard capacitors mainly derives from a choice of dielectric materials which are fused-silica and nano-ceramic. And the capacitors are placed into a constant temperature control system to eliminate the capacitance variance caused by the environment temperature change.