In military electronic products, in order to ensure the reliability of the whole machine system, the following principles shall be followed when selecting electrolytic capacitors:

(1) to select as many components as possible to be included in the QPLs of military electronic components;

(2) to select the products of the selected components list as far as possible;

3) selecting the quality grade of components correctly;

(4) selecting standard and general components as far as possible, and choosing new and non-standard components with caution;

In providing the list of components, it is necessary to be clear about the meaning of the marking of the components, and avoid purchasing components that do not meet the reliability requirements of the whole machine system.

     When selecting capacitors, designers should understand the main technical properties of electrolytic capacitors. The capacitance, working voltage, leakage current, tangent value of loss angle, temperature characteristic, impedance frequency characteristic, reverse voltage resistance, storage performance and price are compared. At the same time, we should pay attention to the material used in the capacitor, the most commonly used material is Z5U, this material has stable performance, high dielectric coefficient, large capacitor capacity, self-resonant frequency can reach 120 MHz, and can be used up to 50 MHz. Another commonly used material is NPO, which has good high frequency properties, but has low dielectric constant and low capacity, and is generally not used below 10 MHz.