Multilayer Coil Zn2SiO4 Interface Bonding

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Solution Overview

Problem

Conventional multilayer coil components face challenges in securing bonding strength at the interface between ferrite element bodies due to differing thermal expansion coefficients and shrinkage rates of green sheets with different compositions during calcination.

Innovation Solution

Incorporating Zn2SiO4 as a constituent component in both ferrite element body portions, with optional buffer layers and varying ZnO and NiO content rates, to enhance bonding strength between the ferrite element body portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If green sheets of two types having different compositions are overlapped and integrated to create ferrite element bodies with different compositions, then impedance characteristics can be adjusted, but bonding strength at the interface between ferrite element bodies deteriorates due to different thermal expansion coefficients and shrinkage rates during calcination

Engineering Contradiction:

Improveimpedance characteristicsVSAvoidbonding strength at interface

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies parameter changes by modifying the chemical composition parameters of the green sheets. Specifically, it controls the ZnO content within 5-50 wt% and SiO2 content within 5-50 wt% ranges in both types of green sheets. This parameter adjustment ensures that both ferrite element bodies contain Zn2SiO4 after calcination, which resolves the bonding strength issue while maintaining the ability to adjust impedance characteristics through composition variations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by incorporating Zn2SiO4 as a common phase in both ferrite element bodies. The green sheets are designed as composite materials containing ferrite powder, ZnO, SiO2, and other components. The formation of Zn2SiO4 composite phase at the interface creates a bonding bridge between the two different composition ferrite element bodies, solving the interface bonding problem while allowing impedance tuning through overall composition control.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If green sheets with different compositions are used to form ferrite element bodies, then thermal expansion coefficients and shrinkage rates differ during calcination, but this makes it difficult to secure bonding strength at the interface

Engineering Contradiction:

Improvecomposition variationVSAvoidbonding strength at interface

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent addresses thermal expansion and shrinkage differences by changing the compositional parameters of the green sheets. By ensuring both types contain ZnO (5-50 wt%) and SiO2 (5-50 wt%), the patent creates a common Zn2SiO4 phase that forms during calcination. This parameter control compensates for the different thermal behaviors of the two green sheet types, ensuring reliable interface bonding despite composition variations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces Zn2SiO4 as an intermediary phase at the interface between the two ferrite element bodies. This intermediary compound forms from the reaction of ZnO and SiO2 in the green sheets during calcination. The Zn2SiO4 phase acts as a mediator that accommodates the thermal expansion and shrinkage differences between the two green sheet types, maintaining interface bonding strength despite the differing thermal properties.

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

The inclusion of Zn2SiO4 significantly improves the bonding strength at the interface between the ferrite element body portions, and the addition of buffer layers further enhances this strength, leading to a more robust multilayer coil component.

Implementation Method 1

both the first element body portion and the second element body portion contain Zn2SiO4 as a constituent component... a bonding strength at the interface between the first element body portion and the second element body portion is improved

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

a buffer layer interposed between the first element body portion and the second element body portion... the bonding strength between the first element body portion and the second element body portion can be further improved

Methodology Applied

Scientific EffectStress distribution:

Data Source

PatentUS11367559B2Multilayer coil component

Publication Date: 2022.06.21 TDK CORP

AI summary

The inventors have newly found that, even when a composition of a first element body portion and a composition of a second element body portion are different from each other, a high bonding strength at an interface between the first element body portion and the second element body portion can be obtained when both the first element body portion and the second element body portion contain Zn2SiO4 as a constituent component. That is, when the first element body portion and the second element body portion contain Zn2SiO4, a bonding strength at the interface is improved compared to a case in which the first element body portion and the second element body portion do not contain Zn2SiO4.