Technical Reference

Typical Tan Delta for Polypropylene Film Capacitors

Tan δ (dissipation factor) tells you how "lossy" a capacitor is. Polypropylene film capacitors have the lowest tan δ of any polymer dielectric — but what values are actually normal? This guide gives you the numbers.

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What Is Tan Delta (Dissipation Factor)?

Tan δ is the ratio of the energy dissipated (wasted as heat) to the energy stored per cycle. It is defined as:

tan δ = ESR / X_C = ESR × 2πfC

Where ESR = equivalent series resistance, X_C = capacitive reactance, f = frequency, C = capacitance

A tan δ of 0.0002 means that for every 10,000 units of energy stored, only 2 units are lost as heat per cycle. This is why PP film capacitors are used in applications where efficiency matters — power factor correction, high-frequency filtering, audio crossovers, and resonant circuits.

Tan δ vs DF vs Q: Tan δ and Dissipation Factor (DF) are the same thing. Quality Factor (Q) is the reciprocal: Q = 1/tan δ. A tan δ of 0.0002 = Q of 5,000.

Typical Tan δ by Dielectric Type

Comparison of dissipation factors across common capacitor dielectrics. Values at 1kHz, 25°C.

Dielectric Type	Typical Tan δ @ 1kHz	DF (%)	Quality Factor (Q)
Polypropylene (PP)	0.0001 – 0.0005	0.01 – 0.05%	2,000 – 10,000
Polystyrene (PS)	0.0001 – 0.0003	0.01 – 0.03%	3,000 – 10,000
Polyphenylene Sulfide (PPS)	0.0005 – 0.002	0.05 – 0.2%	500 – 2,000
Polyester (PET)	0.005 – 0.015	0.5 – 1.5%	70 – 200
Polyethylene Naphthalate (PEN)	0.004 – 0.010	0.4 – 1.0%	100 – 250
Ceramic C0G/NP0	0.0001 – 0.001	0.01 – 0.1%	1,000 – 10,000
Ceramic X7R	0.01 – 0.025	1 – 2.5%	40 – 100
Aluminum Electrolytic	0.05 – 0.30	5 – 30%	3 – 20

PP Film Tan δ vs Frequency

One of PP's key advantages is how stable its tan δ remains across frequency:

Frequency	Typical PP Tan δ	Typical PET Tan δ	Notes
100 Hz	0.0001	0.004	Power line frequency
1 kHz	0.0002	0.008	Standard test frequency
10 kHz	0.0003	0.012	Audio range
100 kHz	0.0005	0.020	Switching PS frequency
1 MHz	0.001	0.035	RF applications

Where Low Tan δ Matters Most

Power Factor Correction (PFC)

High AC currents flow through PFC capacitors continuously. Low tan δ means less heat, higher efficiency, and longer life.

Audio Crossover Networks

Low-loss capacitors maintain signal integrity and prevent frequency-dependent attenuation that colors the sound.

Resonant / Tank Circuits

High Q (low tan δ) maintains sharp resonance peaks. Essential for oscillators, filters, and tuned circuits.

Snubber Circuits

Snubbers absorb high-frequency transients. Low tan δ prevents excessive heating from repeated charge/discharge cycles.

High-Frequency Filtering

PP's stable tan δ across frequency ensures consistent filtering performance from audio to RF ranges.

Precision Timing / Sample-and-Hold

Low dielectric absorption (related to tan δ) prevents voltage "memory" effects that corrupt timing accuracy.

Tan Delta FAQ

What does tan delta mean in a capacitor?

Tan delta (tan δ), also called dissipation factor (DF), measures how much energy a capacitor wastes as heat relative to the energy it stores. It is the ratio of the ESR to the capacitive reactance: tan δ = ESR / Xc = ESR × 2πfC. A lower tan δ means less energy loss and less heat generation.

What is a typical tan delta for polypropylene (PP) film capacitors?

Polypropylene film capacitors have exceptionally low tan δ, typically between 0.0001 and 0.0005 (0.01% to 0.05%) at 1kHz. This makes PP the lowest-loss polymer dielectric available. Even at 100kHz, PP film capacitors typically stay below 0.001 (0.1%). This is why PP capacitors are preferred for resonant circuits, audio crossovers, and precision timing.

How does polypropylene compare to polyester (PET) in tan delta?

Polypropylene (PP) has roughly 10× lower tan δ than polyester (PET). Typical values at 1kHz: PP = 0.0002, PET = 0.005–0.01. Polyphenylene sulfide (PPS) falls in between at roughly 0.001. For applications where loss matters (audio, RF, power factor correction), PP is the clear choice.

Does tan delta change with frequency?

Yes. For PP film capacitors, tan δ increases slightly with frequency but remains very low up to several hundred kHz. At 1MHz and above, parasitic inductance (ESL) dominates and the capacitor approaches self-resonance. The excellent frequency stability of PP is one of its key advantages over polyester.

Does tan delta change with temperature?

Minimally for PP. Polypropylene has excellent temperature stability of tan δ across its operating range (-55°C to +85°C typical). The dissipation factor stays remarkably constant until you approach the glass transition temperature. This is another reason PP is preferred for precision applications.

When should I choose polypropylene over other film types?

Choose PP when you need: 1) Lowest possible losses (audio crossovers, resonant circuits), 2) High-frequency stability (RF filtering, snubbers), 3) High pulse/ripple current handling (power electronics), 4) Tight capacitance tolerance (timing circuits), 5) Long life with minimal drift. Choose polyester when cost matters more than loss performance.

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