Multilayer Coil Structure With Glass-Ferrite Interface Adhesion
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Solution Overview
Problem
The existing multilayer coil components face issues with insufficient adhesion between the dielectric glass layer and the magnetic material layer, which affects the performance and reliability of the coil.
Innovation Solution
A coil component design featuring a bare body with a first glass layer sandwiched between a first ferrite layer and a second ferrite layer, where the area rate of pores and average crystal particle size in specific regions are optimized to enhance adhesion, including a first inner region with a higher pore area rate and smaller crystal size within the first ferrite layer, and similar optimizations in the second ferrite layer, to improve bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional multilayer coil component structure is used, then the manufacturing process is simple, but the adhesion between the dielectric glass layer and the magnetic material layer becomes insufficient
Solution Approach 1:
The ferrite layer is divided into three distinct regions (first inner region, first intermediate region, and first outer region) with different pore area rates and crystal particle sizes. The first inner region has a higher pore area rate and smaller crystal particle size to enhance adhesion to the glass layer, while other regions have different properties optimized for their specific functions. This local differentiation of material properties resolves the contradiction by providing enhanced adhesion only where needed at the glass-ferrite interface.
Solution Approach 2:
The ferrite layer is segmented into multiple regions with different microstructures. By dividing the ferrite layer into distinct zones with varying pore densities and crystal sizes, the invention creates a gradient structure that optimizes both adhesion at the interface and overall layer performance, thereby improving reliability without requiring complete structural redesign.
2Reliability
If the pore area rate and crystal particle size are optimized in specific regions, then the adhesion between layers is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The invention specifies precise local characteristics for different regions of the ferrite layer, including pore area rates (e.g., 5-30% in the first inner region) and crystal particle size ranges (e.g., 1-5 μm in the first inner region versus 3-7 μm in the first outer region). These localized specifications enable targeted adhesion enhancement while providing clear manufacturing guidelines for each region.
Solution Approach 2:
The invention controls multiple parameters including pore area rate, crystal particle size, and region-specific microstructural characteristics. By establishing specific parameter ranges for each ferrite layer region (such as pore area rates of 5-30% in the first inner region versus 3-15% in the first outer region), the patent enables precise control over adhesion properties while maintaining manufacturability through defined parameter specifications.
Data Source
AI summary
A coil component includes a bare body including, in a lamination direction, a first glass layer, a first ferrite layer adjacent to one principal surface side of the first glass layer, and a second ferrite layer adjacent to the other principal surface side of the first glass layer, a coil inside the first glass layer, and outer electrodes on surfaces of the bare body and electrically connected to the coil. Assuming that a region between first and second positions is a first inner region, a region between third and fourth positions is a first outer region, and a region between the second and fourth positions is a first intermediate region, an area rate of pores in the first inner region is greater than in the first intermediate region, and an average crystal particle size of ferrite in the first inner region is smaller than in the first intermediate region.