Name: /Tools-Info/Fedri962l
Brand: EstiSource
Availability: InStock

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FEDRI962L Film Capacitor (Polyester/Polypropylene)

is a metallized plastic-film capacitor. Film capacitors consist of two conductive electrodes separated by a thin plastic dielectric, storing energy in the electric field between them. In FEDRI962L the dielectric is a composite of PET and PP films. Such capacitors combine the high capacitance density of PET (higher dielectric constant) with the very low loss of PP, making them suitable for a range of DC and AC applications. Typical uses include DC blocking/decoupling, noise suppression, and AC power factor correction, as well as high-frequency filtering and timing circuits. PET enables compact size and high-temperature use, while PP provides superior stability at high frequencies. Both films can be plain or metallized: a thin aluminum layer is vacuum-deposited on the film to form the electrodes, combining compact design with self-healing properties (small faults vaporize the metal).

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EstiSource provides a digital platform tailored for sourcing components like FEDRI962L. Engineers can enter the part details and quickly get a cost estimate of the component, and generate RFQs to multiple suppliers. The platform “helps you estimate your product costs quickly and connect with trusted suppliers for customized quotes, all in one place”. This streamlined workflow – combining costing tools with an extensive supplier database – lets teams compare manufacturers and pricing side-by-side. With EstiSource, buyers save time by automating the RFQ and costing process, ensuring estimates match target costs before production.

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EstiSource is designed to give procurement and engineering teams speed, structure, and confidence in their sourcing decisions. Key benefits include fast, accurate part-cost estimation and immediate access to vetted suppliers for components like film capacitors. As the company emphasizes, its platform delivers “fast and reliable product cost estimation” along with “seamless RFQ generation” and an “extensive supplier database”. By using EstiSource, organizations can significantly reduce sourcing costs and optimize their supply chain – all through a single, easy-to-use interface.

1. Material Composition

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2. Manufacturing Process

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3. Challenges and Limitations

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Despite their advantages, polyester/polypropylene film capacitors have some constraints:

Dielectric Loss

Polyester (PET) has a relatively high dissipation factor. As a result, PET-based capacitors exhibit higher dielectric loss, making them unsuitable for prolonged high-voltage AC service. They are mainly used in DC or low-frequency AC circuits. PP film, by contrast, has very low loss but is typically used up to only ~1000 V in practice.

Temperature and Stability

PET capacitors can operate up to ~125°C, whereas PP films generally max out around 100–105°C. PET’s capacitance also shifts with temperature (often +3–+6% from –20 to +100°C), while PP shifts about –3% over the same range. High-temperature derating may be needed.

Mechanical Sensitivity

PP film has lower tensile strength than PET. PP rolls are more stretchable and can elongate if wound too tightly. Both films can generate static charge during winding and attract dust if not properly controlled.

Size and Capacitance

Film capacitors are relatively bulky compared to ceramic or electrolytic caps for the same capacitance. Single-unit capacitances above a few µF become large and expensive. Also, film caps are non-polar, so they cannot replace polarized electrolytics in circuits requiring polarity.

Cost and Voltages

Typical film capacitors are low-voltage types (tens to hundreds of volts). Special high-voltage film caps exist (film/oil or special housings) but are more costly. Exceeding the rated voltage or temperature can puncture the film, though metallized types will usually “self-heal” a small breakdown by vaporizing the metal at the fault point.

4. Costing

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5. Properties and Characteristics

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Low Dielectric Loss: Film capacitors exhibit extremely low dissipation (tan δ). For PP, tan δ can be ~0.02% at 1 kHz, and even PET film is only ~0.5%. This yields very high quality factor (Q) and low self-heating under AC stress.

High Insulation Resistance

Properties: Both PET and PP have very high volume resistivity. Typical insulation resistance is on the order of 10⁴–10⁵ MΩ·µF. This means leakage currents are negligible and capacitors hold charge very well over time.

Dielectric Constant & Size

Properties: PET’s dielectric constant (~3.2) is higher than PP’s (~2.2). Thus, PET allows more capacitance in a given volume, giving compact packages. PP’s lower εr makes its parts larger for the same value.

Self-Healing

Properties: In metallized-film construction, the thin metal layer can “self-heal”. A local dielectric breakdown vaporizes the tiny metal spot, isolating the fault without shorting the capacitor. This greatly enhances reliability under transient stress.

Stability

Properties: Capacitance tolerance is typically ±5% to ±10%, with tighter tolerances (±1–2%) available. Both PET and PP are stable dielectrics: PP has a negative temperature coefficient (about –200 ppm/°C) while PET’s is positive (~+400 ppm/°C). In practice, PP capacitors change only a few percent over –40°C to +80°C, whereas PET may shift up to +5–6%. Both are far more stable than electrolytics.

Voltage and Frequency

Properties: FEDRI962L devices are non-polar and can handle AC or DC. Typical rated voltages range from a few volts up to hundreds of volts; specialized film caps go to 1 kV or more. The low ESR/ESL of film types supports high ripple currents and frequencies. They have excellent high-frequency response (no piezoelectric effects) and can be used up into the MHz range.

Durability

Properties: Film capacitors have long lifetime and exhibit minimal aging. They tolerate surge pulses well (especially PP types), and the strong polymer dielectrics resist breakdown. However, excessive mechanical shock or moisture (for PET) should be avoided.

6. Frequently Asked Questions

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What applications are polyester/polypropylene film capacitors used for?

Typically in circuits requiring stable, low-loss capacitance: AC power filters, motor-run snubbers, SMPS DC-link capacitors, signal coupling/decoupling, and timing networks. They are common in audio crossovers, power supplies, inverters, and RF circuits. In general, film caps are chosen for low dissipation (e.g. PP for high-frequency or AC work) and PET for compact DC decoupling.

How do polyester and polypropylene dielectrics differ?

Polyester (PET) has a higher dielectric constant, so it packs more capacitance in a small volume, and it tolerates higher temperatures (up to ~125°C). Polypropylene (PP) has very low dielectric loss and better capacitance stability, but a lower max temperature (~100°C) and slightly larger size for equal capacitance. PET is often used in general-purpose and DC applications, whereas PP is preferred for precision, pulse, and AC duties.

What is self-healing in film capacitors?

In a metallized-film capacitor, the electrode is an extremely thin metal layer deposited on the film. If a breakdown occurs, the metal at that point vaporizes and isolates the fault, leaving the rest of the capacitor intact. This “self-healing” prevents catastrophic failure and maintains reliability over time.

Are these capacitors polarized?

No. Film capacitors like FEDRI962L are non-polar, meaning they can be used in either orientation for AC or DC. Their polymer dielectric has no polarity, unlike electrolytics which require correct polarity.

What is the typical temperature coefficient?

Polypropylene film has a slightly negative temperature coefficient (on the order of –200 ppm/°C), while polyester is positive (+400 ppm/°C). In absolute terms, neither tends to drift much; for example, a PP capacitor may change only ~–3% from –25°C to +85°C, whereas a PET unit may shift +5–6%. These values are far better than most polarized caps.

How should I choose between PET and PP film?

It depends on the application. For high-frequency, pulse, or AC use, PP-film capacitors are ideal due to their low loss and high pulse/current capability. For smaller DC-blocking caps or cost-sensitive designs, PET (polyester) film is often chosen for its compact size and lower cost. Always check the voltage and temperature ratings required by your circuit.