薄膜電容器的容量大小取決于薄膜金屬層面積的大小，所以容量的下降主要就是金屬鍍層受外界因素影響，面積減少而產生的。

　　The capacity of thin film capacitor depends on the area of metal layer, so the decrease of capacity is mainly caused by the reduction of metal coating area affected by external factors.

　　在電容器制作過程中，膜層之間存在微量的空氣，且較難完全消除。電容器工作時，空氣在電場作用下，有可能被電離。空氣電離后產生臭氧，臭氧是一種不穩定的氣體，常溫下自行分解為氧，是一種強氧化劑，低濃度下可瞬間完成氧化作用。

　　In the process of capacitor fabrication, there is a trace of air between the films, which is difficult to eliminate completely. When the capacitor works, the air may be ionized under the action of electric field. Ozone is a kind of unstable gas, which can decompose into oxygen at room temperature. It is a strong oxidant, and it can complete oxidation instantly at low concentration.

　　金屬化薄膜的金屬鍍層（成份為Zn/Al）遇到臭氧分解的氧后立即氧化，生成透明不導電的金屬氧化物ZnO和Al2O3，實際表現為板面積減小，電容器容量下降。因此消除或減少膜層間的空氣，可以減緩電容量衰減。

　　The metal coating (Zn / Al) of the metallized film will be oxidized immediately when it meets the oxygen decomposed by ozone, resulting in transparent and non-conductive metal oxides ZnO and Al2O3. The actual performance is that the plate area decreases and the capacitor capacity decreases. Therefore, eliminating or reducing the air between the films can slow down the capacitance attenuation.

　　當膜層間的空氣被外界水份侵入時，空氣的擊穿電位會降低，加快空氣電離，產生大量的臭氧，氧化金屬化薄膜的金屬鍍層，電容器的容量會迅速下降。

　　When the air between the film layers is invaded by external water, the breakdown potential of the air will be reduced, which will accelerate the air ionization and produce a large amount of ozone. The capacitance of the capacitor will decrease rapidly when the metal coating of the metallized film is oxidized.