Solid Electrolytic Capacitor Anode Thin-Thickness Portion Design

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Solution Overview

Problem

Conventional solid electrolytic capacitors exhibit insufficient thermal shock resistance, leading to capacitance loss when exposed to high-temperature environments due to crack formation and stress concentration at the anode leading part, particularly during the formation of the anode thin-thickness portion.

Innovation Solution

The design includes an anode body with a cathode forming portion and an anode thin-thickness portion, where the porous portion is either compressed or removed to prevent crack formation, and the anode thin-thickness portion is connected to the anode terminal, reducing stress concentration and fatigue fracture, and a resin package body encloses the capacitor element to manage thermal expansion differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the porous portion is compressed or removed to form an anode thin-thickness portion, then stress concentration and fatigue fracture are reduced, but the structural integrity and mechanical strength of the anode body may be compromised

Engineering Contradiction:

Improvethermal shock resistanceVSAvoidmechanical strength of anode body

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The anode body is designed with non-uniform porous layer thickness, creating a thin-thickness portion with reduced porous layer thickness compared to other regions. This local variation in structure allows the specific area to have different mechanical properties (lower stress concentration) while the rest of the anode maintains its structural integrity and strength.

Inventive Principle:

Principle #3Local quality

2Reliability

If the porous portion is completely removed in the anode thin-thickness portion, then crack formation is prevented, but the capacitance and energy storage capacity are reduced

Engineering Contradiction:

Improvecrack resistanceVSAvoidcapacitance

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The porous layer is selectively removed only in the thin-thickness portion of the anode body, while being maintained in other regions. This localized removal prevents crack formation and stress concentration in the critical thin-thickness area, while preserving the capacitance-providing porous structure in other portions of the anode.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The anode body is divided into different regions with different porous layer configurations: a thin-thickness portion with reduced or removed porous layer for mechanical stability, and other portions with full porous layer for capacitance. This segmentation allows each region to fulfill its specific function optimally.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11417471B2Solid electrolytic capacitor and production method thereof

Publication Date: 2022.08.16 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

Disclosed is a solid electrolytic capacitor 1 including capacitor elements 2A to 2C, an anode terminal 4, and a resin package body enclosing at least the capacitor elements, the capacitor elements 2A to 2C each including an anode body 6 having a porous portion as a surface layer, a dielectric layer 7, and a cathode part 8 covering at least part of the dielectric layer 7. The anode body 9 has a cathode forming portion and an anode thin-thickness portion adjacent to the cathode forming portion. The dielectric layer 7 covers at least part of a surface of the porous portion in the cathode forming portion. The porous portion is removed in the anode thin-thickness portion or is thinner in the anode thin-thickness portion than in the cathode forming portion. The anode body is connected to the anode terminal 4 at the anode thin-thickness portion.