A) Metalized film capacitors have electrical characteristics that change depending on the environmental conditions in which they are placed, and the degree of capacity change varies depending on the material of the inductor and the construction of the outer material.

B) Noise problem: The noise generated by the capacitor is due to the mechanical vibration between the two poles of the film of the inductor through the action of AC power. The noise problem, especially when the voltage is unstable or there are voltage surges or the capacitor is used in high frequency, will produce a high vibration sound, but it does not affect the electrical characteristics of the capacitor itself, and the volume frequency of the noise will change from batch to batch.

C) Custody methods and storage conditions

1. Humidity, dust reactive and acidifying gas (hydrophobic, acidifying hydrophobic, to sulfuric acid gas) will have a deteriorating effect on the solder terminal of the external electrode of the capacitor.

2. Especially avoid the high temperature and humidity environment, keep it at -10~40℃, humidity below 85%, and do not expose it to water or moisture directly to avoid moisture intrusion and damage the capacitor. 

D) Issues to be noted when using

1. Capacitors must be avoided in environments with rapid changes in voltage and temperature. Even if the rated value of the capacitor is not exceeded, it can cause rapid deterioration of the capacitor quality.

2. When capacitors are used in circuits with rapid or frequent charging and discharging, special frequencies such as high frequency or different atmospheric pressure, etc., it is necessary to confirm the suitability of capacitors.

3. When capacitors are connected in parallel, capacitors must be connected in series with resistors for capacitor withstand voltage test, life test, etc.

4. If the capacitor is subjected to abnormal over-voltage, over-temperature or at the end of product life, and the insulation material is damaged, the capacitor may smoke and burn up. To prevent such a situation, it is necessary to use a protective type capacitor, so that the capacitor is open to the circuit when it occurs, to achieve the effect of protection.

E) If you see or smell smoke from the capacitor, immediately isolate the power supply to avoid disaster.

F) The specification of the capacitor is based on the product specification. If the user is not compatible or exceeds the rated use, the scope of the application must be rechecked.

G) If the capacitor case is a plastic product, such as PBT, the surface of the case will be slightly depressed due to factors such as injection molding and the shrinkage rate of the plastic itself, and the finished product will also be depressed. This is not due to the manufacturing problem of the capacitor.

H) Reliability test standard: rated voltage*1.25/600 hours/rated temperature.

– Mr. Guangyu Chen, film capacitor expert from Taiwan, China