Statistical Variations in the Parasitic Capacitance of a Coil

Abstract:
The used materials and the wire placement have some uncertainties in the production process of an inductor and influence its parasitic capacitance. This study investigates the importance of precise placement of the turns and the deviation in capacitance, dependent on geometrical variations and manufacture tolerances. An ETD 60/30/20 core is wound, and measured 100 times, and compared to simulative results. The results show a direct influence of the shifted wire and a normal distribution of the capacitance. Combined deviations in the production process cause uncertainties of similar magnitude, with variations of up to 13.64% in extreme cases.