Conductive Polymer Capacitor Sealing for Moisture Barrier Reliability

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Solution Overview

Problem

Existing capacitor elements suffer from degradation due to oxygen and moisture permeation through the sealing layer, leading to decreased electrostatic capacity, increased equivalent series resistance (ESR), and potential delamination.

Innovation Solution

Incorporating a sealing layer with a first insulating resin and flattened inorganic fillers oriented in a surface direction orthogonal to the thickness direction to hinder the diffusion of oxygen and moisture, while maintaining electrical connectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional sealing layer is used, then the structure is simple and easy to manufacture, but oxygen and moisture permeate through the sealing layer causing degradation of the conductive polymer

Engineering Contradiction:

Improveresistance to oxygen and moisture permeationVSAvoidsealing layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sealing layer is constructed as a composite material containing both organic resin and inorganic filler particles. This composite structure provides superior barrier properties against oxygen and moisture permeation compared to conventional single-material sealing layers, while maintaining manufacturability through standard lamination processes.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The inorganic filler particles are distributed throughout the sealing layer to create localized barrier regions. These filler particles create a tortuous path for oxygen and moisture diffusion, enhancing the barrier effect specifically at the sealing layer without requiring structural modifications to other components.

Inventive Principle:

Principle #3Local quality

2Duration of action of stationary object

If the sealing layer is made more impermeable to oxygen and moisture, then the lifetime characteristics improve, but the manufacturing complexity increases

Engineering Contradiction:

Improvelifetime characteristicsVSAvoidsealing layer fabrication

Core Design Contradiction:

Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The permeability parameters of the sealing layer are modified by incorporating inorganic filler particles with specific properties (size, shape, distribution). This changes the diffusion characteristics of oxygen and moisture through the sealing layer, extending the lifetime characteristics while using standard manufacturing parameters and processes.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively prevents the permeation of oxygen and moisture, enhancing the lifetime characteristics of the capacitor element by suppressing degradation of the conductive polymer in the solid electrolyte layer and improving thermal conductivity.

Implementation Method 1

first flattened inorganic fillers oriented in a surface direction orthogonal to a thickness direction in a portion of the sealing layer that covers the capacitor unit

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

improving thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250391613A1Capacitor element

Publication Date: 2025.12.25 MURATA MFG CO LTD

AI summary

A capacitor element that includes: a capacitor unit including an anode plate including a core portion and a porous portion on at least one main surface of the core portion, a dielectric layer on a surface of the porous portion, and a cathode layer that includes a solid electrolyte layer on a surface of the dielectric layer, and the solid electrolyte layer contains a conductive polymer; and a sealing layer covering the capacitor unit, wherein the sealing layer contains a first insulating resin and first flattened inorganic fillers, and the first flattened inorganic fillers are oriented in a surface direction orthogonal to a thickness direction in a portion of the sealing layer that covers the capacitor unit.