Thin film capacitors are a type of capacitor that uses plastic film as the dielectric, with advantages such as small size, light weight, good stability, and strong self-healing ability. They are widely used in fields such as power electronics, communication, home appliances, and new energy. The following are the main categories, characteristics, applications, and selection points of thin film capacitors:
1、 Classified by medium material
Polyester film capacitor (PET)
Medium: Polyethylene Terephthalate.
characteristic:
Low cost: suitable for large-scale production.
Temperature stability is generally average: the capacity changes by about ± 5% with temperature.
Limited high-frequency performance: applicable frequency ≤ 1MHz.
Application: General power filtering, home appliances, audio equipment.
Common models: CL11, CL21, X2-PET.
Polypropylene film capacitor (PP)
Medium: Polypropylene.
characteristic:
Low loss: The dielectric loss tangent (tan δ) is low, and the high-frequency performance is excellent.
High insulation resistance: high withstand voltage strength, low leakage current.
Good temperature stability: The capacity changes by about ± 2% with temperature.
Application: High frequency power supply, communication equipment, electromagnetic compatibility (EMC) filtering, electric vehicle charging station.
Common models: MKP-X2, MKP-Y2, CBB22.
Polyphenylene sulfide film capacitor (PPS)
Medium: Polyphenylene sulfide.
characteristic:
High temperature resistance: Wide working temperature range (-55 ℃ to+150 ℃).
High stability: Long term use with minimal capacity changes.
Chemical corrosion resistance: suitable for harsh environments.
Applications: automotive electronics, aerospace, industrial control.
Common models: PPS-X2, PPS-Y2.
Polyethylene terephthalate film capacitor (PEN)
Medium: Polyethylene Naphthalate.
characteristic:
High temperature resistance: Wide working temperature range (-55 ℃ to+150 ℃).
High dielectric constant: high capacity density.
Radiation resistance: suitable for special environments.
Applications: Aerospace, military electronics, high-voltage direct current transmission (HVDC).
Common models: PEN-X2, PEN-Y2.
2、 Classified by structural form
Foil film capacitor
Structure: Made by winding metal foil as the electrode and dielectric material.
characteristic:
Large capacity: suitable for high current applications.
Good stability: Long term use with minimal capacity changes.
Large volume: not suitable for high-density circuit boards.
Applications: Power electronics, industrial control, audio equipment.
Common models: CL11, CL21.
Metalized thin film capacitor
Structure: Metal film is deposited on the surface of the medium as an electrode.
characteristic:
Self healing ability: When local breakdown occurs, the metal film can evaporate and restore insulation.
Compact size: With the same capacity, the volume is smaller than that of foil capacitors.
Wide capacity range: from pF level to μ F level.
Applications: High frequency circuits, pulse circuits, electromagnetic compatibility (EMC) filtering.
Common models: MKP-X2, MKP-Y2, CBB81.
Stacked Thin Film Capacitor (MLCB)
Structure: Composed of multiple layers of thin films and electrodes alternately stacked.
characteristic:
Compact size: suitable for high-density circuit boards.
Excellent high-frequency characteristics: low equivalent series inductance (ESL) and high self resonant frequency.
Capacity stability: low temperature coefficient.
Applications: 5G base stations, medical equipment, aerospace.
Common models: MLCB-X2, MLCB-Y2.
3、 Classified by application scenario
Power filter film capacitor
Features: Large capacity, high voltage resistance, low ESR.
Application: Switching power supply, LED driver, charger.
Selection: X2/Y2 capacitor combination is used to suppress differential and common mode interference.
Electromagnetic Compatibility (EMC) Thin Film Capacitors
Features: Good high-frequency performance, low loss, high stability.
Applications: Communication equipment, industrial control, medical equipment.
Selection: MKP-X2/Y2 or stacked film capacitor.
Pulse power thin film capacitor
Features: High pulse current tolerance, low inductance.
Applications: laser power supply, electromagnetic pulse weapon, particle accelerator.
Selection: High voltage polypropylene film capacitor or specially designed pulse capacitor.
High Voltage Direct Current Transmission (HVDC) Thin Film Capacitors
Features: high voltage resistance, low loss, high reliability.
Application: High voltage direct current transmission system, flexible alternating current transmission (FACTS).
Selection: PEN or PPS film capacitors to ensure long-term stability.
4、 Classified by security level
Safe film capacitor
Definition: Thin film capacitors that have undergone safety certification (such as UL, ENEC, CQC) and are designed specifically to prevent electric shock and electromagnetic interference.
characteristic:
X capacitor (X1/X2/X3): Connected across power lines to suppress differential mode interference.
Y capacitor (Y1/Y2/Y3/Y4): Connected across the power line and ground to suppress common mode interference.
Applications: Home appliances, industrial equipment, power adapters.
Selection: Prioritize X2/Y2 capacitors, balancing safety and cost.
5、 Key parameters for selection
Rated voltage: It needs to be 1.25 times higher than the actual working voltage (such as selecting a 315VAC capacitor for a 250VAC circuit).
Capacity: Choose based on filtering or energy storage requirements, excessive capacity may increase costs.
ESR: High frequency circuits should choose models with ESR<10m Ω.
Temperature range: For extreme environments, products should be selected between -55 ℃ and+150 ℃.
Package size: In space limited scenarios, surface mount or miniaturized packaging is preferred.
Safety certification: Must comply with safety standards such as UL, ENEC, CQC, etc. (for safety capacitors).
6、 Typical application scenarios
Home appliances: LED drivers use X2/Y2 film capacitors to suppress power line interference.
Communication equipment: 5G base stations use MKP-X2 thin film capacitors to resist high-frequency signal loss.
Automotive electronics: The electric vehicle charging station uses polypropylene film capacitors to ensure high current filtering stability.
Aerospace: The satellite power system uses stacked thin-film capacitors to resist radiation and vibration.
By reasonable classification and selection, thin film capacitors can fully leverage their advantages such as small size, good stability, and excellent high-frequency characteristics to meet diverse circuit needs.