Soldering requirements for film capacitors and dielectric withstand voltage damage

1. Soldering requirements for film capacitors

The loss of film capacitor is generally divided into dielectric loss and metal loss. The dielectric loss is generally the loss caused by dielectric leakage current and dielectric polarization. The metal loss is generally the contact resistance between the plate and the pin, the contact plate resistance, and the pin resistance. Part of the composition to control the loss of the film resistance, to be controlled from the above factors, mainly depends on the process technology of the film capacitor.

The soldering process is the outer lead wire soldering to the metal layer on the end face of the capacitor core, which is also the main part of the high frequency loss. After welding, the following requirements should be met:

(1) Select the outer lead wire of the capacitor according to the requirements, and the exposed length of the lead wire should meet the requirements;

(2) The lead wire soldering joint should be appropriate, and should be welded to the height of the end face of the capacitor core at 23, and the lead wire should be less than 0.5 mm from the middle;

(3) The lead wire should be straight and firm, and there should be no soldering or soldering;

(4) The lead wire should be able to withstand a pulling force of 1 kg or more.

2. Pressure damage of film capacitor dielectric

Since the value of the loss D at a local weak point in the capacitor medium is large, a large local heat is generated at a non-uniform high field strength to damage the medium. When a DC voltage is applied, heat is generated only by leakage current. Especially for newly produced capacitors, the insulation resistance is generally high, the leakage current is small, and the possibility of local overheating damage is very small.

In addition, if the applied AC voltage reaches the initial partial discharge voltage value, the partial discharge will be repeated and deteriorated every half cycle to cause local damage. In the case of DC voltage, even if there is an initial partial discharge, it is necessary to re-accumulate after the charge is dissipated to generate partial discharge. In summary, it can be concluded that the flow withstand voltage may cause serious damage to the capacitor medium, and the DC withstand voltage can basically be said to be no damage detection, or at least a detection method with little damage.