Coil Component Resin Coating Dielectric Strength

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Solution Overview

Problem

Coil components using drum cores face challenges in achieving high dielectric breakdown voltage due to the low dielectric strength of thin coated conductive wires, which can be further compromised by resin coating degradation and wire movement during heating processes like thermo-compression bonding or laser bonding.

Innovation Solution

A coil component design featuring coated conductive wires with a resin coating layer where the maximum space between wires in the first winding layer is narrower than the wire diameter, inhibiting wire movement and enhancing dielectric breakdown voltage, along with a manufacturing method that forms a resin coating layer by melting the resin film to fill defects and prevent resin coating layer thickness from causing stress on the wires.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a thin coated conductive wire is used to decrease the size of the coil component, then the inductance requirement can be met, but the dielectric strength voltage becomes insufficient

Engineering Contradiction:

Improvesize of coil componentVSAvoiddielectric strength voltage

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent uses a composite structure consisting of a conductive wire core coated with an insulating layer and further covered with a resin coating layer. This multi-layer composite structure provides both the electrical conductivity needed for inductance and the dielectric strength for voltage insulation, resolving the contradiction between miniaturization and dielectric performance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and chemical parameters of the coating materials, specifically using a resin with a low melting point that can fill scars and cracks when heated. This parameter change enhances the dielectric strength without increasing the wire diameter, allowing miniaturization while maintaining voltage insulation

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If thermo-compression bonding or laser bonding is used to connect wires to terminal electrodes, then electrical connection is achieved, but heat degrades the coating film and reduces dielectric strength voltage

Engineering Contradiction:

Improvewire connectionVSAvoiddielectric strength voltage

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies a resin coating layer beforehand that serves as a protective cushion for the insulating coating film. When heat is applied during wire bonding, this resin layer absorbs and distributes the thermal stress, preventing degradation of the underlying insulating coating and maintaining dielectric strength despite the necessary thermal processing for electrical connection

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a thick resin film is used to fill defects and improve dielectric breakdown voltage, then dielectric strength increases, but high stress on the conductive wire during cooling causes great displacement of conductor filaments

Engineering Contradiction:

Improvedielectric breakdown voltageVSAvoidposition of conductor filaments

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent carefully controls the thickness parameter of the resin film and selects resin materials with appropriate thermal and mechanical properties. This optimized parameter selection allows the resin to fill defects and improve dielectric breakdown voltage while minimizing thermal stress and filament displacement during the heating and cooling process

Inventive Principle:

Principle #35Parameter changes

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

The approach results in a coil component with improved dielectric breakdown voltage without compromising magnetic properties or solder wettability, as the resin coating layer is confined to the winding core and not the flange portions, ensuring high reliability and performance.

Implementation Method 1

a manufacturing method that forms a resin coating layer by melting the resin film to fill defects

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

heat that is applied at the time of wire connection is conveyed via core material of the coated conductive wire

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10186376B2Coil component comprising a plurality of coated conductive wires and manufacturing method thereof

Publication Date: 2019.01.22 TDK CORP

AI summary

Disclosed herein is a coil component that includes: a drum core including a first flange portion, a second flange portion and a winding core portion positioned between the first and second flange portions; a plurality of coated conductive wires forming a first winding layer wound around the winding core portion and a second winding layer wound around the winding core portion with an intervention of the first winding layer; and a resin coating layer covering the coated conductive wires. A maximum space between the coated conductive wires in the first winding layer is narrower than a diameter of the coated conductive wires.