BFC238314394 vs BFC238311394
| Part Number |
|
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| Category | Film Capacitors | Film Capacitors |
| Manufacturer | Vishay Beyschlag/Draloric/BC Components | Vishay Beyschlag/Draloric/BC Components |
| Description | CAP FILM 0.39UF 5% 400VDC RADIAL | CAP FILM 0.39UF 5% 400VDC RADIAL |
| Package | Bulk | Bulk |
| Series | MMKP383 | MMKP383 |
| Features | - | - |
| Operating Temperature | -55°C ~ 105°C | -55°C ~ 105°C |
| Mounting Type | Through Hole | Through Hole |
| Package / Case | Radial | Radial |
| Applications | High Pulse, DV/DT | High Pulse, DV/DT |
| Tolerance | ±5% | ±5% |
| Size / Dimension | 1.024" L x 0.394" W (26.00mm x 10.00mm) | 1.024" L x 0.394" W (26.00mm x 10.00mm) |
| Termination | PC Pins | PC Pins |
| Voltage Rating - AC | 200V | 200V |
| Voltage Rating - DC | 400V | 400V |
| Lead Spacing | 0.886\" (22.50mm) | 0.886\" (22.50mm) |
| Ratings | - | - |
| Height - Seated (Max) | 0.768\" (19.50mm) | 0.768\" (19.50mm) |
| Capacitance | 0.39 µF | 0.39 µF |
| ESR (Equivalent Series Resistance) | - | - |
| Dielectric Material | Polypropylene (PP), Metallized | Polypropylene (PP), Metallized |

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1. What are the uses of film capacitors?
High-frequency filtering, power decoupling, power noise bypass
The main uses of film capacitors include high-frequency filtering, power decoupling, power noise bypass, etc. In electronic devices, film capacitors are widely used in various circuits due to their high insulation impedance, wide frequency response and self-healing properties.
Specific application scenarios
High-frequency filtering: Film capacitors have excellent high-frequency insulation performance, and the capacitance and loss angle are independent of frequency in a large frequency range and change little with temperature, so they are often used in high-frequency filtering circuits.
Power decoupling: In car audio systems, film capacitors are used for power decoupling to ensure stable power supply and avoid noise caused by feedback generated by the power supply.
Power noise bypass: Film capacitors are also widely used for power noise bypass (reverse cross-connection) to reduce the impact of power noise on the circuit.
Different types of applications
CBB film capacitors: widely used in circuit boards because of their high insulation impedance and wide frequency response.
Organic film capacitors: Made of materials such as polypropylene film and polyester film, they have excellent performance, a wide variety of varieties, and a wide range of applications. They are suitable for a variety of electronic devices.
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2. Are film capacitors better than electrolytic capacitors?
Not necessarily
Film capacitors and electrolytic capacitors each have their own advantages and disadvantages, and the specific choice depends on the application scenario.
Advantages of film capacitors
Non-polarity: Film capacitors are non-polar, and there is no need to distinguish between positive and negative poles, avoiding the risk of capacitor explosion due to reverse connection.
Long life: Film capacitors have significantly longer life and better stability.
Wide temperature range: Film capacitors have a wide operating temperature range, generally -40℃~+105℃/110℃, suitable for various ambient temperatures.
High withstand voltage: Film capacitors can withstand overvoltages higher than 1.5 times the rated voltage in a short period of time, and have strong withstand voltage.
Low loss: Film capacitors have low loss and are suitable for high-frequency circuits, especially for occasions requiring low loss and high-frequency applications.
Advantages of electrolytic capacitors
Large capacity: Electrolytic capacitors usually have large capacitance and are suitable for occasions requiring large amounts of energy storage.
Low cost: The cost of electrolytic capacitors is relatively low, suitable for occasions with strict cost requirements.
High energy density: Electrolytic capacitors are a strong choice when cost-effective, high-capacity energy storage is required, especially when maintaining DC output voltage during power outages.
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3. Will the performance of film capacitors degrade?
Yes
The performance of film capacitors will degrade. The performance degradation of film capacitors is mainly due to their internal structure and material properties.
Reasons for performance degradation
Metal plating oxidation: During the capacitor manufacturing process, there is a trace amount of air between the film layers, which may be ionized under the action of the electric field to produce ozone. Ozone is a strong oxidant that oxidizes the metal plating to produce non-conductive metal oxides, resulting in a reduction in the plate area and a decrease in the capacitor capacity.
Humid air: During the winding process of film capacitors, if the workshop environment is not properly controlled, there will be a large amount of humid air. These humid air will produce air ionization reactions when the capacitor is working, generating ozone, which further causes the capacitor capacity to decay.
Poor quality materials: The film materials used are of poor quality, such as uneven evaporation and defects on the film, which will cause the capacitor capacity to decay.
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4. Can film capacitors be used for AC?
Yes
Film capacitors can be used for AC. Film capacitors can work normally in AC circuits and have specific application scenarios and advantages.
Structure and working principle of film capacitors
Film capacitors are mainly composed of metal foil (or foil obtained by metallizing plastic) as electrode plates and plastic film as dielectric. Common plastic films include polyethylene, polypropylene, polystyrene or polycarbonate. These capacitors are usually made by winding or stacking processes to form a cylindrical structure.

