Film Capacitor String-Shaped Electrode Projections

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Solution Overview

Problem

Existing film capacitors face challenges in reducing size while maintaining or improving capacitance, leading to insufficient adhesiveness between electrode films and external electrodes, which affects electrical connectivity and increases dielectric loss.

Innovation Solution

The film capacitor design incorporates electrode films with string-shaped projection portions that act as spacers, enhancing adhesiveness by creating gaps for external electrodes to enter, thereby improving electrical connectivity and reducing dielectric loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the size of the film capacitor is reduced, then the capacitance density is improved, but the adhesiveness between electrode films and external electrodes deteriorates

Engineering Contradiction:

Improvecapacitor sizeVSAvoidadhesiveness

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The electrode film is designed with projection portions that protrude toward the dielectric film before the external electrode is applied. This preliminary structural preparation ensures that when the external electrode is later applied, it can effectively enter and adhere to the projection portions, solving the adhesion problem in miniaturized capacitors

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of uniformly thickening the electrode film throughout, the invention creates localized projection portions that protrude in specific areas. This local quality change provides enhanced adhesion points exactly where the external electrode needs to bond, while keeping the overall electrode film thickness reduced for miniaturization

Inventive Principle:

Principle #3Local quality

2Volume of moving object

If the electrode film thickness is reduced, then the capacitance density is improved, but the electrical connectivity deteriorates

Engineering Contradiction:

Improveelectrode film thicknessVSAvoidelectrical connectivity

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The invention transitions from a two-dimensional uniform electrode film to a three-dimensional structure with projection portions. These projections add vertical dimensionality, creating gaps that allow external electrodes to penetrate and establish better electrical contact, thereby improving connectivity without increasing overall film thickness

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If the film capacitor size is reduced, then the productivity is improved, but the dielectric loss increases

Engineering Contradiction:

Improvecapacitance densityVSAvoiddielectric loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The projection portions act as intermediary structures between the electrode film and the external electrode. By creating gaps through these projections, external electrodes can more effectively enter and bond to the electrode film, reducing contact resistance and thereby reducing dielectric loss in miniaturized capacitors

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10607784B2Film capacitor, combination type capacitor, inverter, and electric vehicle

Publication Date: 2020.03.31 KYOCERA CORP

AI summary

A film capacitor includes a wound body in which a dielectric film and an electrode film are wound; and a pair of external electrodes provided respectively on a pair of end faces positioned in an axial direction of the wound body. The dielectric film includes an electrode-free portion provided on one end side in a width direction, continuously in a longitudinal direction of the dielectric film. The electrode film has a first projection portion on a surface on the other end side in the width direction, and the first projection portion has a string shape extending in the width direction.