Oblique Cut Anode Substrate for Solid Electrolytic Capacitor

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Solution Overview

Problem

Existing solid electrolytic capacitors face challenges in achieving high capacitance and low impedance due to uneven thickness of the electrically conducting polymer layer, leading to increased leakage current and short-circuit failures, especially when stacking capacitor elements.

Innovation Solution

The method involves cutting an anode substrate obliquely to create a chamfered edge with grooves, which facilitates uniform formation of the electrically conducting polymer film, preventing direct contact between elements and reducing leakage current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thick solid electrolyte film is formed to completely cover the inside of fine pores and outer surface, then high capacitance and low impedance characteristics are achieved, but the thickness of the solid electrolyte layer increases which is not suitable for multilayer capacitor fabrication

Engineering Contradiction:

Improvecapacitance and impedance characteristicsVSAvoidsolid electrolyte layer thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The invention applies different surface treatments to different parts of the electrode foil. The cut surface receives a specific treatment (chamfering or rounding) to create a localized structure that promotes uniform polymer deposition, while other areas maintain their original characteristics. This local modification enables thin yet uniform electrolyte coverage.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electrode foil undergoes preliminary surface treatment (chamfering or rounding of cut surfaces) before the solid electrolyte formation process. This pre-treatment creates optimal surface geometry that ensures uniform polymer deposition and complete pore coverage even at reduced electrolyte thickness.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If conventional cutting methods are used on electrode foil, then production efficiency is maintained, but burrs are generated on the cut edge which causes short-circuit failures

Engineering Contradiction:

Improveproduction efficiencyVSAvoidshort-circuit failure rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention converts the potentially harmful burrs generated during cutting into beneficial surface features. By chamfering or rounding the cut surfaces, the irregular burr structures are transformed into controlled geometric features that promote uniform solid electrolyte deposition and prevent short-circuit failures.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention changes the geometric parameters of the cut surface by applying chamfering or rounding treatments. This modifies the surface topology from sharp, irregular edges to controlled angles or curved surfaces, fundamentally altering how the solid electrolyte deposits on the electrode foil.

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

This approach results in a stable, thin capacitor element with reduced short-circuit failures, increased capacitance, and consistent equivalent series resistance, enabling the production of high-capacity solid electrolytic multilayer capacitors.

Implementation Method 1

The method involves cutting an anode substrate obliquely to create a chamfered edge with grooves

Methodology Applied

Scientific EffectMechanical cutting:

Implementation Method 2

an electrolytic oxidative polymerization method and a chemical oxidative polymerization method are generally known

Methodology Applied

Scientific EffectOxidative polymerization:

Data Source

PatentUS7495892B2Solid electrolytic capacitor

Publication Date: 2009.02.24 MURATA MFG CO LTD

AI summary

The present invention relates to an anode substrate for a solid electrolytic capacitor which is produced by cutting obliquely a metal substrate comprising a valve-acting metal layer having fine pores and a valve-acting metal layer without fine pores, and having a cut surface which is formed by elongation of the valve-acting metal layer without fine pores dragged by a cutting blade; particularly to an anode substrate for a solid electrolytic capacitor which is produced by cutting obliquely a metal substrate comprising a valve-acting metal layer having fine pores and a valve-acting metal layer without fine pores, and a layer of the elongated valve-acting metal which is generated by that the valve-acting metal layer without fine pores is elongated being dragged along with a cutting blade and covers the edge part of the valve-acting layer having fine pores meets the requirement represented by the following formula:0≦y/z≦1 [Formula 1]wherein y represents the thickness of the layer of the elongated valve-acting metal in the direction of the thickness of the substrate and z represents the thickness of the valve-acting layer having fine pores which is in contact with the elongated metal layer in the direction of the thickness of the substrate, respectively; and to a solid electrolytic capacitor comprising the above-mentioned anode substrate, an edge of which is chamfered at least partially.