Electrolytic Capacitor Polymer Composition for Low ESR at High Heat

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Solution Overview

Problem

Existing electrolytic capacitors using conductive polymers like PEDOT face challenges in further increasing capacitance and maintaining low equivalent series resistance (ESR) and dielectric dissipation factor tan δ, especially when exposed to high temperatures.

Innovation Solution

The use of a conductive polymer containing a first monomer unit corresponding to a 3,4-ethylenedioxythiophene compound and a second monomer unit corresponding to a 3,4-dialkoxythiophene compound, which improves the affinity and covering property of the conductive polymer on the dielectric layer, enhancing electrostatic capacity and thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional conductive polymer like PEDOT is used, then the electrolytic capacitor achieves basic conductivity, but the electrostatic capacity is limited and ESR increases at high temperatures

Engineering Contradiction:

Improveelectrostatic capacity and thermal stabilityVSAvoidESR increase at high temperature

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies composite materials by combining two different conductive polymer types: PEDOT (poly(3,4-ethylenedioxythiophene)) and P3AT (poly(3-alkylthiophene)) or its derivatives. This composite conductive polymer layer integrates the high conductivity of PEDOT with the thermal stability and low ESR characteristics of P3AT, resolving the contradiction between maintaining basic conductivity and reducing high-temperature ESR increase.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent employs parameter changes by adjusting the composition ratio between PEDOT and P3AT in the conductive polymer layer, controlling the molecular weight and structure of the polymers, and optimizing the deposition conditions. These parameter adjustments enable fine-tuning of the conductive polymer's properties to achieve both high electrostatic capacity and thermal stability while minimizing ESR increase at elevated temperatures.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the conductive polymer coverage on the dielectric layer is increased, then electrostatic capacity improves, but the dielectric dissipation factor tan δ increases

Engineering Contradiction:

Improveelectrostatic capacityVSAvoiddielectric dissipation factor

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating a conductive polymer layer with spatially varying composition and structure. The PEDOT-P3AT composite provides different local properties: PEDOT-rich regions provide high conductivity for charge storage, while P3AT-rich regions provide thermal stability and control interfacial properties. This local differentiation allows high electrostatic capacity while controlling energy loss through optimized local composition at the dielectric-conductive polymer interface.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If a single-type conductive polymer is used, then the manufacturing process is simple, but the affinity and covering property on the dielectric layer are insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidaffinity and covering property

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-synthesizing both PEDOT and P3AT polymers with controlled molecular weights and structures before combining them in the conductive polymer layer. This preliminary preparation ensures that each polymer component has optimized properties for its specific function, achieving high affinity and covering property on the dielectric layer while maintaining a relatively simple manufacturing process through sequential or simultaneous deposition of the pre-prepared polymers.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration secures high electrostatic capacity, maintains a low dielectric dissipation factor tan δ, and reduces the change in ESR when exposed to high temperatures, thereby stabilizing the quality of the electrolytic capacitor.

Implementation Method 1

a conductive polymer covering a part of the dielectric layer... improves the affinity and covering property of the conductive polymer on the dielectric layer, enhancing electrostatic capacity

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Implementation Method 2

maintains a low dielectric dissipation factor tan δ

Methodology Applied

Scientific EffectDielectric dissipation: Dielectric

Implementation Method 3

reduces the change in ESR when exposed to high temperatures, thereby stabilizing the quality of the electrolytic capacitor

Methodology Applied

Scientific EffectThermal stability: Heat Treatment

Data Source

PatentUS12266482B2Electrolytic capacitor and method for producing same

Publication Date: 2025.04.01 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An electrolytic capacitor includes a capacitor element. The capacitor element includes an anode body including a dielectric layer on a surface of the anode body, and a conductive polymer covering a part of the dielectric layer. The conductive polymer contains a first monomer unit corresponding to a 3,4-ethylenedioxythiophene compound and a second monomer unit corresponding to a 3,4-dialkoxythiophene compound.