Laminated Coil Component Pore Barrier for Ni Diffusion

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Solution Overview

Problem

The diffusion of Ni from magnetic layers into non-magnetic layers during firing in open-magnetic-circuit-type laminated coil components reduces the thickness of the non-magnetic layer, affecting the direct-current superposition characteristic and causing variations in inductance characteristics, especially in smaller components.

Innovation Solution

Incorporating pores in the low-magnetic-permeability or magnetic layers to prevent Ni diffusion, where the pores function as non-magnetic material and are filled with resin to improve strength and maintain the non-magnetic layer's thickness, thereby reducing the contact area and minimizing Ni diffusion during firing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic layers are fired at high temperature to achieve good electrical characteristics, then the inductance characteristic improves, but Ni diffuses into the non-magnetic layer reducing its thickness and degrading direct-current superposition characteristic

Engineering Contradiction:

Improveinductance characteristicVSAvoidthickness of non-magnetic layer

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

A protective coating layer is formed on the non-magnetic layer before the firing process. This coating acts as a barrier to prevent Ni diffusion during the high-temperature firing process, allowing the magnetic layers to be fired at high temperature to achieve good inductance characteristics while maintaining the thickness and non-magnetic properties of the non-magnetic layer.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protective coating layer serves as an intermediary barrier between the magnetic layers and the non-magnetic layer. During firing, this intermediate layer prevents direct contact and diffusion between Ni in the magnetic layers and the non-magnetic layer, enabling high-temperature processing without compromising the non-magnetic layer's integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the thickness of the non-magnetic layer is reduced to improve direct-current superposition characteristic, then the open-magnetic-circuit structure effectiveness increases, but Ni diffusion from magnetic layers becomes more severe

Engineering Contradiction:

Improvedirect-current superposition characteristicVSAvoidNi diffusion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protective coating is applied to the non-magnetic layer before assembly and firing, establishing a preventive barrier against Ni diffusion. This allows the non-magnetic layer to maintain its designed thickness and open-magnetic-circuit functionality while being protected from Ni infiltration during subsequent high-temperature processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protective coating acts as an intermediary barrier that physically separates the magnetic layers from the non-magnetic layer during firing. This intermediate layer blocks the diffusion path of Ni atoms, preventing them from migrating into the non-magnetic layer while allowing the structure to maintain its intended thickness proportions.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the contact area between magnetic layer and non-magnetic layer is increased to improve electrical connection, then the inductance increases, but Ni diffusion pathway is expanded

Engineering Contradiction:

ImproveinductanceVSAvoidNi loss from magnetic layer

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The protective coating is formed on the non-magnetic layer surface before the magnetic layers are attached. This pre-formed coating creates a diffusion barrier that allows the magnetic layers to be positioned with optimal contact area for high inductance while preventing Ni from diffusing into the non-magnetic layer through the coated surface.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protective coating serves as an intermediary layer at the interface between magnetic and non-magnetic layers. It maintains good electrical contact and magnetic coupling while simultaneously blocking the diffusion pathway for Ni atoms, thus allowing large contact area without increasing Ni loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 maintains the thickness of the non-magnetic layer, enhancing the direct-current superposition characteristic and reducing variations in electrical characteristics, ensuring consistent performance even with increased current.

Implementation Method 1

Ni included in the magnetic layers diffuses into the non-magnetic layer

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

pores are provided in at least one sub-layer defining the low-magnetic-permeability layer

Methodology Applied

Scientific EffectPorosity: Porosity

Data Source

PatentUS7719399B2Laminated coil component

Publication Date: 2010.05.18 MURATA MFG CO LTD

AI summary

A laminated coil component includes high-magnetic-permeability ferrite layers that are disposed on both main surfaces of a low-magnetic-permeability ferrite layer. Pores or pores filled with a resin are formed in the low-magnetic-permeability ferrite layer. Nickel in the high-magnetic-permeability ferrite layers does not significantly diffuse into the pores or the pores filled with the resin during firing, and thus, Ni does not readily diffuse into the low-magnetic-permeability ferrite layer.