Porous External Electrode Structure for Reliable Capacitor Lead Bonding

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Solution Overview

Problem

Existing capacitors face issues with low connection reliability between the external electrode and the lead terminal due to the mechanical weakness caused by forming projections and recesses on the lead terminal, which reduces mechanical strength and may not improve connection reliability for all materials.

Innovation Solution

The external electrode is designed with a porosity of 8% to 20%, which enhances bonding strength and adhesion with the lead terminal, eliminating the need for projections and recesses, thereby improving connection reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If projections and recesses are formed on the lead terminal to improve connection, then connection reliability is improved, but mechanical strength of the lead terminal is reduced causing it to break

Engineering Contradiction:

Improveconnection reliabilityVSAvoidmechanical strength of lead terminal

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The external electrode is designed with a porous structure having a porosity of 5% to 20%, which allows the lead terminal to mechanically interlock with the electrode material within the pores during bonding, achieving strong connection without compromising lead terminal strength

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The porosity parameter of the external electrode is optimized to a specific range (5%-20%) to balance connection strength and electrical performance, providing adequate mechanical interlocking while maintaining electrical conductivity

Inventive Principle:

Principle #35Parameter changes

2Reliability

If deep recesses are formed in the lead terminal to ensure fixation, then connection fixation is improved, but the lead terminal becomes weaker and more prone to breaking

Engineering Contradiction:

Improveconnection fixationVSAvoidlead terminal strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

Instead of modifying the lead terminal with recesses (conventional approach), the invention inverts the approach by creating a porous structure in the external electrode that actively engages with the lead terminal surface, achieving fixation without compromising lead terminal integrity

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The porous external electrode structure provides multiple anchoring points within its pores for the lead terminal, distributing mechanical stress and achieving strong fixation without requiring deep recesses in the lead terminal

Inventive Principle:

Principle #31Porous 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 capacitor achieves high connection reliability and secure electrical contact with reduced mechanical weakness, maintaining electrical performance and reducing variations in adhesion among products.

Implementation Method 1

the external electrode has a porosity of 8% to 20%. Thereby, the bonding between the external electrode and the lead terminal is strengthened

Methodology Applied

Scientific EffectPorosity: Porosity

Data Source

PatentUS12586725B2Capacitor having an external electrode with increased porosity

Publication Date: 2026.03.24 MURATA MFG CO LTD

AI summary

A capacitor that includes: a capacitor element; an external electrode on an end face of the capacitor element; and a lead terminal bonded to the external electrode, wherein the external electrode has a porosity of 8% to 20%. The external electrode may be a metallikon electrode. The external electrode may also contain an alloy of zinc and aluminum.