With the rise of new energy vehicles

the development trend of electric vehicles is rapid

and the demand of metallized film capacitor is more and more due to its unique advantage in this field. The integrated module of electric vehicles is generally compact in structure but weak in heat dissipation

which makes the metallized capacitor to operate in the high temperature and high humid environment. Therefore how to improve the high temperature and humid resistance perofrmance of the metallized fim capacitor becomes gradually an important study subject. In this paper

the related concepts and standards of constant humidity and heat are introduced

the capacitance attenuation reaction mechanism of metallized film capacitor in constant humidity and heat (double 85) test is studied and the purpose of double 85 test (accelerating aging to expose defects in the early failure stage of capacitor) is described. Double 85 test is carried out on X2 products by constant temperature and humidity chamber

and the core of the product is dissected to reveal the missing metal layer inside the metallized film and corresponding analysis is made. The suggestion of the metallized film capacitor passing double 85 test is proposed so to provide theoretical and test base for the capacitor in high damp and hest resistance.