Polymer Dopant Copolymer Moisture Resistance Electrolytic Capacitor

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Solution Overview

Problem

Existing electrolytic capacitors face challenges in achieving sufficient moisture resistance and restoration function due to the hydration reaction of hydrophilic groups in the polymer dopant, leading to increased equivalent series resistance (ESR) and risk of short-circuiting.

Innovation Solution

Incorporating a polymer dopant with a copolymer structure that includes units derived from monomers with sulfonate, carboxy, and hydroxy groups, which undergo intramolecular or intermolecular condensation to form esters, reducing hydrophilicity and improving moisture resistance while maintaining restoration function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a polymer dopant with hydrophilic groups (sulfonate, carboxy) is used to provide restoration function, then the restoration function is improved, but moisture resistance deteriorates due to hydration reaction

Engineering Contradiction:

Improverestoration functionVSAvoidmoisture resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the polymer dopant by introducing a copolymer structure containing both hydrophilic groups (for restoration function) and hydrophobic groups (for moisture resistance). This parameter change allows the material to simultaneously achieve good restoration function and moisture resistance by balancing the properties of different functional groups within the same polymer structure.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional polymer dopants are used to achieve low ESR, then electrical conductivity is improved, but moisture resistance deteriorates leading to increased ESR over time

Engineering Contradiction:

Improveelectrical conductivityVSAvoidmoisture resistance

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent creates a composite polymer dopant structure by copolymerizing monomers with different functional groups. The resulting copolymer combines the electrical conductivity-providing hydrophilic groups with the moisture resistance-providing hydrophobic groups, achieving a composite material that simultaneously delivers low initial ESR and long-term moisture resistance.

Inventive Principle:

Principle #40Composite materials

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

The proposed solution effectively enhances moisture resistance and restoration function, reducing ESR and leakage current, thereby improving the reliability and performance of electrolytic capacitors.

Implementation Method 1

units derived from monomers with sulfonate, carboxy, and hydroxy groups, which undergo intramolecular or intermolecular condensation to form esters

Methodology Applied

Scientific EffectCondensation reaction:

Implementation Method 2

The conductive polymer layer includes a π-conjugated polymer and a dopant. With use of the dopant, high conductivity is imparted to the π-conjugated polymer

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS10388463B2Electrolytic capacitor and conductive polymer dispersion

Publication Date: 2019.08.20 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An electrolytic capacitor includes an anode body, a dielectric layer formed on the anode body, and a conductive polymer layer covering at least a part of the dielectric layer. The conductive polymer layer includes a conductive polymer and a polymer dopant. The polymer dopant includes a first copolymer including: (A) a first unit derived from a first monomer having a sulfonate group; (B) a second unit derived from a second monomer having a carboxy group; and (C) a third unit derived from a third monomer having a hydroxy group.