Solid Electrolytic Capacitor Boundary Protection

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Solution Overview

Problem

Conventional solid electrolytic capacitors with partially etched anode foils are prone to cracks and damage due to stress vulnerabilities at the boundary between etched and unetched surfaces, leading to instability and poor quality.

Innovation Solution

A solid electrolytic capacitor design featuring an anode foil with both etched and unetched surfaces, where an insulating protective layer covers the boundary and ends of the cathode lead-out and solid electrolyte layers to enhance mechanical strength and prevent damage, along with a manufacturing method involving specific steps for forming these layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If etching is provided to all or part of the surface of the metal foil to increase capacitance, then the capacitance of the capacitor element is improved, but the boundary part between etched and unetched surfaces becomes vulnerable to stress and prone to cracks

Engineering Contradiction:

ImprovecapacitanceVSAvoidstress resistance at boundary

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by forming an insulating protective layer specifically at the boundary part between etched and unetched surfaces of the anode foil. This localized protection addresses the stress vulnerability at the boundary region without affecting the capacitance-enhancing etching structure. The protective layer is applied selectively where needed rather than uniformly across the entire surface.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements beforehand cushioning by pre-forming an insulating protective layer at the boundary part before the capacitor is subjected to operational stress. This protective layer acts as a preventive measure that cushions the boundary region against potential cracks and stress concentration, ensuring reliability before failures can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of manufacture

If a resin coating film is formed as a masking member on a part of the main surface of the metal foil, then etching can be performed selectively, but the boundary part between etched and unetched surfaces remains vulnerable to damage

Engineering Contradiction:

Improveselective etching capabilityVSAvoidboundary part stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent addresses the boundary vulnerability by applying a localized insulating protective layer specifically at the boundary part between etched and unetched surfaces. This selective protection maintains the ease of selective etching manufacturing process while adding targeted reinforcement where the boundary is most vulnerable to stress and damage.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The insulating protective layer acts as an intermediary element between the etched and unetched surfaces at the boundary part. This intermediate layer provides mechanical support and stress distribution, mediating the transition between the two different surface regions and preventing direct stress concentration at the boundary interface.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If the anode foil has a partially etched surface to increase capacitance, then the energy storage capacity is improved, but the capacitor element becomes prone to internal short circuits and degradation

Engineering Contradiction:

Improveenergy storage capacityVSAvoidresistance to internal short circuit and degradation

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by forming an insulating protective layer specifically at the boundary part of the anode foil, where stress concentration and potential failure points occur. This localized protection maintains the high capacitance benefits of partial etching while providing targeted protection against internal short circuits and degradation at the vulnerable boundary region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The insulating protective layer is formed beforehand at the boundary part to prevent future internal short circuits and degradation. This preventive measure cushions the boundary region against electrical breakdown and mechanical failure, ensuring long-term reliability of the high-capacitance capacitor structure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11127533B2Solid electrolytic capacitor and method for manufacturing same

Publication Date: 2021.09.21 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A solid electrolytic capacitor includes a capacitor element. The capacitor element includes an anode foil, a dielectric layer, a solid electrolyte layer, and a cathode lead-out layer. The anode foil includes a first part and a second part other than the first part. The first part has an etched surface, and a second part has an unetched surface. The dielectric layer is formed on the etched surface of the first part in the anode foil. The solid electrolyte layer is formed on at least a part of a surface of the dielectric layer. The cathode lead-out layer is formed on at least a part of a surface of the solid electrolyte layer. An insulating protective layer covers a boundary part between the first part and the second part as well as an end of the cathode lead-out layer and an end of the solid electrolyte layer.