Capacitive Isolator With High-Low Permittivity Insulating Layers

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Solution Overview

Problem

Existing isolators face reliability issues under high voltage due to increased electric field intensity at the outer lower corner of the coil portion, leading to potential breakdown and reduced insulation performance.

Innovation Solution

The isolator design incorporates a second insulating layer with higher permittivity and a third insulating layer with lower permittivity, strategically positioned below the coil portion to divide the applied voltage and reduce electric field intensity, combined with a protective insulating layer to enhance structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single structure with one set of electrodes is used, then the structure is simplified and signal transmission performance is improved, but the electric field intensity increases leading to reduced reliability under high voltage

Engineering Contradiction:

ImprovestructureVSAvoidelectrode reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

An insulating layer is introduced as an intermediary between the two electrodes. This insulating layer includes a high permittivity portion that strategically modifies the electric field distribution, reducing intensity at critical regions (outer lower corner of coil portion) while maintaining overall signal transmission capability. The intermediary layer prevents direct electrical contact, thereby improving reliability without significantly increasing structural complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The insulating layer is not uniformly distributed but features a high permittivity portion located specifically at the outer lower corner region of the coil portion. This local variation in permittivity creates a non-uniform electric field distribution that reduces stress concentration at critical points, thereby improving electrode reliability without requiring a complete redesign of the overall structure.

Inventive Principle:

Principle #3Local quality

2Device complexity

If most of the applied voltage is concentrated on one set of electrodes, then the structure remains simple, but the electric field intensity increases causing potential breakdown

Engineering Contradiction:

Improvevoltage distribution structureVSAvoidelectric field intensity

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The permittivity parameter of the insulating layer is strategically varied by introducing a high permittivity portion in specific regions. This parameter change allows the electric field to be redistributed - the high permittivity region attracts and concentrates electric field lines, reducing the field intensity at the outer lower corner of the coil portion where breakdown is most likely to occur, while maintaining overall voltage transmission.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The high electric field intensity, which initially causes harmful effects like breakdown and warpage, is converted into a beneficial distribution pattern. By placing the high permittivity portion at the outer lower corner, the electric field is intentionally concentrated in this region, which paradoxically reduces the field intensity at the electrode surfaces and prevents breakdown, thereby converting the harmful high field effect into a protective mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 increases the coupling coefficient, improves transfer efficiency, and suppresses breakage of the coil portion, thereby enhancing the reliability and reducing warpage of the isolator by distributing the electric field effectively.

Implementation Method 1

divide the applied voltage and reduce electric field intensity

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 2

second insulating layer with higher permittivity and a third insulating layer with lower permittivity

Methodology Applied

Scientific EffectPermittivity: Dielectric Permittivity

Implementation Method 3

signals are transmitted or received by dielectric coupling or capacitive coupling between two electrodes

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 4

signals are transmitted or received by dielectric coupling or capacitive coupling between two electrodes

Methodology Applied

Scientific EffectDielectric coupling: Dielectric

Data Source

PatentUS11605868B2Isolator

Publication Date: 2023.03.14 KK TOSHIBA

AI summary

An isolator includes a lower electrode, a first insulating layer, a second insulating layer, an upper electrode, and a low permittivity portion. The first insulating layer is provided on the lower electrode, and includes a protruding portion in an upper portion of the first insulating layer. The second insulating layer is provided on the protruding portion, extends sideways from a region directly above the protruding portion, and has a specific permittivity higher than a specific permittivity of the first insulating layer. The upper electrode is in contact with an upper surface of the second insulating layer. The low permittivity portion is in contact with a side surface of the protruding portion and a lower surface of the second insulating layer. The low permittivity portion has a specific permittivity lower than the specific permittivity of the first insulating layer.