What are the parameters of polymer capacitors?
Date：2025-06-13
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As a new generation of high-performance capacitors, polymer capacitors have a parameter system that combines the commonalities of traditional capacitors with the characteristics of polymer materials. The following analysis is conducted from five dimensions: electrical performance, physical characteristics, environmental adaptability, reliability, and selection logic:
1、 Core electrical performance parameters
Nominal capacity and tolerance
Range: 0.1 μ F to several thousand μ F, with a tolerance typically ranging from ± 5% to ± 20%.
Advantages: The capacity density of polymer tantalum capacitors is 3-5 times that of traditional tantalum capacitors, making them suitable for highly integrated circuits.
Rated voltage (DC)
Features: Wide working voltage range (4V~50V), requiring consideration for derating design (recommended to use at 70% of rated voltage).
Risk: Overvoltage can easily cause electrolyte decomposition, leading to capacity decay or short circuit.
Equivalent series resistance (ESR)
Numerical value: The ESR of polymer aluminum electrolytic capacitors is as low as 5m Ω, which is 90% lower than traditional aluminum electrolysis.
Impact: The lower the ESR, the stronger the ripple current tolerance and the smaller the heat generation, making it suitable for high-frequency decoupling scenarios.
Dielectric loss (tan δ)
Typical value: Polymer tantalum capacitor tan δ ≈ 0.05~0.15, significantly lower than traditional tantalum capacitors (0.2~0.3).
Meaning: The lower the loss, the higher the energy efficiency, suitable for low-power devices.
Leakage current (LC)
Formula: LC=K × C × V (K is a constant, C is capacity, V is voltage).
Advantages: Polymer capacitors reduce leakage current by an order of magnitude compared to traditional aluminum electrolysis, improving circuit stability.
Ripple current tolerance
Definition: The maximum effective value of AC current that a capacitor can withstand at rated temperature.
Parameters: The ripple current of polymer aluminum electrolytic capacitors can reach 3A~5A (100kHz), suitable for output filtering of switching power supplies.
2、 Physical characteristic parameters
Packaging form
Types: Surface mount (SMD), radial lead type, axial lead type.
Trend: SMD packaging accounts for over 80%, such as AVX's TCJ series of surface mount polymer tantalum capacitors, with sizes as small as 0603 (0.6mm × 0.3mm).
Size and volume
Advantage: Under the same capacity, the volume of polymer capacitors is reduced by more than 50% compared to traditional aluminum electrolysis.
Case: Panasonic SP Cap series polymer aluminum electrolytic capacitors, with a diameter of only 4mm and a height of 2.5mm, are suitable for smartphones.
weight
Comparison: Polymer tantalum capacitors weigh only 60% of traditional tantalum capacitors, which is beneficial for lightweight design.
3、 Environmental adaptability parameters
Working temperature range
Standard range: -55 ° C to+105 ° C (some industrial grade can reach+125 ° C).
Characteristics: Polymer electrolyte has small viscosity changes at low temperatures and lower capacity decay than traditional capacitors.
Moisture resistance
Test conditions: Continuous 1000 hours in an environment of 85 ° C/85% RH, with a capacity change of<5%.
Protective measures: Some products are sealed with epoxy resin to enhance their moisture resistance.
Resistance to vibration and impact
Standard: Passed 10-2000Hz vibration test (acceleration 50g) and 50g half sine pulse impact.
Application: Key verification is required in the fields of automotive electronics and aerospace.
4、 Reliability parameters
Life test
Condition: Continuous 2000~5000 hours at rated voltage and high temperature (105 ° C).
Failure mode: Mainly due to electrolyte drying or electrode corrosion, the lifespan of polymer capacitors is extended by 3-5 times compared to traditional aluminum electrolysis.
Self healing properties
Principle: When polymer tantalum capacitors are subjected to overvoltage breakdown, the conductive polymer can quickly oxidize to form an insulating layer, restoring the capacitance function.
Limitation: Multiple self-healing processes may result in a slight decrease in capacity.
High temperature reverse bias test
Condition: Apply reverse voltage (10% of rated voltage) at 125 ° C for 1000 hours.
By standard: leakage current change<100%, verify polarity reversal tolerance.
5、 Application scenarios and selection logic
High frequency decoupling
Parameter priority: ESR<ripple current tolerance<capacity.
Recommended product: AVX's TCS series polymer tantalum capacitors (ESR<10m Ω).
Low power devices
Parameter priority: leakage current<tan δ<capacity stability.
Recommended product: Panasonic SP Cap series polymer aluminum electrolytic capacitors (leakage current<1 μ A).
Extreme environmental applications
Parameter priority: Operating temperature range>Moisture resistance>Vibration tolerance.
Recommended product: KEMET's A700 series polymer tantalum capacitors (-55 ° C~+125 ° C).
6、 Parameter trade-offs and selection recommendations
Capacity and ESR balance: High capacity polymer capacitors may experience an increase in ESR, which needs to be selected based on circuit requirements.
Volume and heat dissipation: Miniaturization packaging may affect heat dissipation performance, and the impact of temperature rise on lifespan needs to be evaluated.
Cost and performance: Polymer capacitors have a cost that is 30% to 50% higher than traditional capacitors, and should be selected based on budget considerations.
By cross comparing data manuals, measured data, and third-party testing reports (such as EEVblog capacitance evaluation), polymer capacitor parameters can be accurately matched with circuit requirements, avoiding performance bottlenecks or failure risks caused by improper selection.
