Multi-layered Solid Electrolytic Capacitor Stress Management

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Solution Overview

Problem

Conventional multi-layered solid electrolytic capacitors face issues with increased leakage current and short circuit defects due to thickness differences between anode and cathode portions, leading to tensile and bending stresses, and horizontal variations in boundary positions during manufacturing.

Innovation Solution

The introduction of an insulative resin layer between the cathode and anode portions and adjacent regions, along with conductive paste connections, reduces stress and prevents short circuits without increasing device size or manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If resistance welding is used to connect anode portions, then electrical connection is achieved, but tensile stress and bending stress are applied to boundaries causing cracks and increased leakage current

Engineering Contradiction:

Improveelectrical connectionVSAvoidboundary strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A resin layer is introduced as an intermediary material between the anode portion and cathode portion boundaries. This resin layer absorbs and distributes the stress generated during resistance welding, preventing direct stress concentration at the vulnerable boundaries. The resin acts as a buffer that maintains electrical connection while protecting the structural integrity of the capacitor elements.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The resin layer is applied in advance to the boundaries of capacitor elements before the stacking and welding process. This pre-application creates a protective cushion that anticipates and mitigates the stress that will be generated during subsequent resistance welding operations, preventing cracks from forming in the first place.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of manufacture

If capacitor elements are stacked with varying boundary positions, then manufacturing flexibility is maintained, but horizontal variations cause short circuit defects

Engineering Contradiction:

Improvestacking flexibilityVSAvoidshort circuit prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The resin layer serves as an intermediary substance that fills and covers the boundaries between capacitor elements. Even when boundary positions vary horizontally during stacking, the resin layer maintains a continuous protective coverage that prevents adjacent electrodes from coming into contact, thereby eliminating short circuit defects while preserving manufacturing flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The resin layer functions as a flexible protective film that can accommodate variations in boundary positions. Its conformal nature allows it to adapt to the actual geometry of the stacked capacitor elements, providing reliable insulation and short circuit prevention regardless of positioning tolerances.

Inventive Principle:

Principle #30Flexible shells and thin films

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 configuration significantly improves product yield by minimizing leakage current and short circuit defects, while maintaining low manufacturing costs and device size.

Implementation Method 1

the insulative resin layer is disposed on a boundary between the cathode portion and the anode portion of at least one of the plurality of capacitor elements and on an adjacent region thereto, wherein one of the anode portions that is adjacent to the anode terminal is fixed to the anode terminal by welding, adjacent ones of the anode portions are fixed to one another by welding

Methodology Applied

Scientific EffectStress distribution:

Implementation Method 2

adjacent ones of the cathode portions are electrically connected to one another by a conductive paste layer

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

each of the capacitor elements comprising an anode body having an anode portion, and a cathode portion having a dielectric oxide film and a cathode layer successively formed on a surface of the anode body

Methodology Applied

Scientific EffectFilm deposition: Deposition (physical)

Data Source

PatentUS7400492B2Multi-layered solid electrolytic capacitor and method of manufacturing same

Publication Date: 2008.07.15 SANYO ELECTRIC CO LTD

AI summary

A multi-layered solid electrolytic capacitor is furnished with a plurality of capacitor elements 6, each having an aluminum foil 1 having an anode portion 7 and a cathode portion 8 having a dielectric oxide film 2 and a cathode layer 3 successively formed on a surface of the aluminum foil 1. The capacitor elements 6 are stacked on each other. Adjacent anode portions 7 of the capacitor elements 6 are welded to one another and adjacent cathode portions 8 are electrically connected one another by a conductive paste layer 18. An insulative resin layer 16 is disposed on a boundary between the cathode portion 8 and the anode portion 7 of at least one of the capacitor elements 6 and on an adjacent region thereto.