Electrode Foil Etching with Edge-Open Masking

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Solution Overview

Problem

Conventional methods for producing electrode foils often result in wrinkles and warpage due to contraction during dielectric layer formation, leading to nonuniformity and potential failure in capacitor elements.

Innovation Solution

A method involving the partial etching of a metal foil using a strip-shaped masking member that covers part of the foil's surface, excluding the side edges, to prevent the etched region from being sandwiched between non-etched regions, thereby reducing contraction-induced wrinkles and warpage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the masking member covers the side edges of the metal foil, then the etched region is fully enclosed by non-etched regions, but this causes significant wrinkle and warpage due to contraction during dielectric layer formation

Engineering Contradiction:

Improveetching uniformityVSAvoidfoil flatness

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The masking member is positioned asymmetrically relative to the metal foil width, deliberately excluding the side edges from coverage. This asymmetric configuration allows the etched region to be open at the sides rather than enclosed, preventing the contraction-induced wrinkle and warpage that occurs when non-etched regions completely surround etched regions during dielectric layer formation

Inventive Principle:

Principle #4Asymmetry

2Shape

If the masking member is positioned away from side edges, then wrinkle and warpage are suppressed, but the etched region configuration changes to be open at sides rather than enclosed

Engineering Contradiction:

Improvefoil flatnessVSAvoidetching pattern control

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

Different regions of the metal foil are given different treatments: the central region is etched while the side edge regions remain unetched. This local differentiation in etching treatment creates a configuration where the etched region is open at the sides, allowing contraction during dielectric layer formation without generating wrinkle and warpage, while still achieving the desired capacitance increase in the etched areas

Inventive Principle:

Principle #3Local quality

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 suppresses wrinkles and warpage in the electrode foil, ensuring a high-quality capacitor with uniform dielectric and cathode extension layers.

Implementation Method 1

partially etching the principal surface of the metal foil by applying current between the metal foil and an electrode while the metal foil faces the electrode via the masking member in etching liquid

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Data Source

PatentUS10607787B2Electrode foil production method and capacitor production method

Publication Date: 2020.03.31 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A method for producing an electrode foil includes: a first step of preparing a metal foil, the metal foil having a strip shape; a second step of disposing a masking member so as to cover part of a principal surface of the metal foil; and a third step of partially etching the principal surface of the metal foil by applying current between the metal foil and an electrode while the metal foil faces the electrode via the masking member in etching liquid after the second step. The masking member has a strip shape. In the second step, the masking member is disposed along a longitudinal direction of the metal foil so as to be separated from both side edges of the metal foil.