Good design of film capacitors typically includes the following characteristics:
1) High insulation resistance: The insulation resistance of a film capacitor should be high to prevent leakage current and ensure stable performance over time.
2) Low ESR and ESL: The equivalent series resistance (ESR) and equivalent series inductance (ESL) of a film capacitor should be low to minimize power loss and ensure high frequency performance.
3) High stability and reliability: Film capacitors should be designed to have a high level of stability and reliability, with minimal changes in capacitance and dissipation factor over time and temperature.
4) Wide temperature range: Film capacitors should be able to operate over a wide temperature range, typically -55°C to +105°C.
5) High voltage rating: Film capacitors should have a high voltage rating to handle high voltage transients and surges.
6) Low self-inductance: Film capacitors should have a low self-inductance to minimize unwanted resonant circuit and high frequency noise.
7) Low leakage current: Film capacitors should have a low leakage current to minimize power loss and heat generation.
8) Durable: Film capacitors should be designed with durable materials that can withstand vibration, shock and other environmental factors.