- PEN film capacitors (SMD/THT)
- PET film capacitors (THT)
- PP film capacitors (THT)
Film capacitors use plastic films as an insulating dielectric. The thin films are wound or layered onto the capacitor. The greater the surface and the smaller the gap between the electrodes, the higher the capacity levels are. This is why the film is applied in extremely thin layers. The many parallel-circuited individual capacitors within the wound film ensure that voltage losses (via the ESR) and the inductance (ESL) are kept low. This means that they are effective up into high frequency ranges, unlike electrolytic capacitors.
Film capacitors have a very low internal resistance, meaning they are suitable for applications with rapid charging and discharging. Thanks to the materials used, film capacitors are self-healing and do not cause a short circuit if there is an internal fault. Using the films as a dielectric minimizes the aging process and maximizes temperature stability.
Film capacitors can exhibit varying characteristics, depending on the (film) material used. The comparisons are made with film capacitors of similar size and design.
PEN (polyethylene naphthalate) film capacitors feature very high temperature stability and are therefore very often used as snubber capacitors in areas subject to thermal stress, such as power supplies.
PET (polyethylene naphthalate, polyester) film capacitors are the best price-performance ratio among film capacitors. They exhibit somewhat higher temperature and frequency sensitivity than PEN or PP capacitors. However, their very thin film can help to achieve far higher capacities than with other films.
PP (polypropylene) film capacitors have a lower capacity in the same design due to their thicker film. However, they feature the lowest loss factor and generate the least heat during charging and discharging.