Main parameters of capacitors for printed circuit boards

- Mar 26, 2019-

(1) Nominal capacity. The nominal capacity of the capacitor is related to the capacitor dielectric material. The nominal capacity series of high-frequency organic thin film dielectric capacitors and ceramic dielectric capacitors is the same as the resistors E24 and E12 series. Among the capacitors with a capacity of 4.7pF or more, the E24 series is used for the nominal capacity series, and the E12 series is used for capacitors with a capacity less than or equal to 4.7pF.

The nominal capacity of electrolytic capacitors such as aluminum, tantalum and niobium is E6 series. The E6 series is used at a capacity of 100pF-1uF; the 1,2.4, 6, 8, 10, 15, 20, 30, 50, 100 series are used at a nominal capacity of 1-100uF.

(2) Allowable error. The allowable error of the electrical appliance is divided into three levels, namely, level 1, ± 5%; level 1 I, ± 10%; level III, ± 20%. Some capacitors have an allowable error of ±5% with J; K indicates an allowable error of ±10%; and M indicates an allowable error of ±20%.

(3) Rated voltage. The maximum voltage effective value that can be continuously applied to the capacitor for a long period of time within the allowable ambient temperature range is called the rated voltage, which is also known as the withstand voltage.

Generally, capacitors with large capacitances and large capacitors have voltage values on the capacitors. Smaller capacitors can only be judged by model. Different types of capacitors have different rated operating voltage ranges.

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(4) Leakage current. Capacitor dielectric material is not an absolute insulator. At a certain operating temperature and voltage, there will always be some current flowing. This current is called leakage current. Among them, the leakage current of the electrolytic capacitor is large, and the leakage current of other types of capacitors is small. Leakage current is usually indicated by the letter 1. 1 Over-conference makes the performance of the capacitor deteriorate, causing circuit failure, and even causing the capacitor to heat up or explode.

(5) Temperature coefficient. The temperature coefficient refers to the degree to which the capacity of the capacitor changes with temperature, using a. Said. The smaller the temperature coefficient of the capacitor, the more stable the circuit operation of the board.

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