jbcapacitors blog

The main properties are Non-polar, high insulation resistance, excellent frequency characteristic (broad frequency response), and the dielectric loss is very small.

Based on the above advantages, film capacitors are widely used in analog circuit. 
Especially in signal coupling part, you must use good frequency characteristic and low dielectric loss of capacitor, to ensure that the signal transmission, when does not have the too big distortion occurs. 

Among all of plastic film capacitors, the most significant is polypropylene (PP) and polystyrene (PS) characteristics of the capacitance.
Film capacitors' manufacturing method usually is the aluminum foil, as the electrode and the plastic film after overlapping winding together. 
But film capacitors have another manufacturing method, called Metallized film (Metallized Film), the method is in plastic film in vacuum evaporation of a very thin layer of metal as electrode.
So you can save the thickness of the electrode foil, reducing the size of the capacitor unit volume. 
It is easy to make film capacitors small, it can make large capacity also.

From jb Capacitors Company sales department