Shortcomings and improvement of Metallized Film Capacitance

In principle, there should be no short-circuit failure mode in metallized film capacitors, and many short-circuit failure phenomena (such as 27-pbxxxx-j0x series) will occur in metallized foil capacitors.Although metallized thin film capacitors have the advantages mentioned above, they also have two disadvantages compared with metal foil capacitors: first, the capacity stability is not as good as that of foil capacitors. This is because metallized capacitors are prone to loss of capacity in long-term working conditions and can lead to capacity reduction after self-healing, so it is used in oscillating circuits which require high capacity stability. Metal foil capacitors should be used better.

Another major drawback is the poor resistance to high current, because the metallized film is much thinner than the metal foil, and the bearing capacity of the large current is weak. In order to improve the defects of metallized thin film capacitors, there have been some improvements in the manufacturing process of high current metallized thin film capacitors at present. The main ways to improve them are

1) using double-side metallized film as electrode;

2) increasing the thickness of metallized coating;

3) improve the welding process of the end metal and reduce the contact resistance.