Coil Component Using Multi-Size Magnetic Powder
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Solution Overview
Problem
Existing coil components face a challenge in increasing inductance while maintaining low core loss, as higher packing density of metal powder leads to increased core loss and degraded DC superposition characteristics.
Innovation Solution
A coil component using a magnetic metal powder containing resin with a combination of first, second, and third metal powders of different average grain diameters, where the first powder has a diameter of 15 μm to 100 μm, the second powder has a diameter of 3 μm to 10 μm, and the third powder has a diameter of 2 μm or less, with a weight ratio of 6:1:1, to enhance magnetic permeability without increasing core loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the packing fraction of metal powder in the magnetic metal powder containing resin is increased to improve magnetic permeability, then the coil inductance increases, but the core loss increases and DC superposition characteristics are degraded
Solution Approach 1:
The metal powder is segmented into three distinct grain diameter ranges (first: 15-100 μm, second: 3-10 μm, third: 2 μm or less), allowing each size fraction to occupy different spatial positions and reduce excessive contact while maintaining high packing density. This segmentation enables the system to achieve high magnetic permeability without the core loss penalties associated with uniformly high packing fractions.
2Reliability
If the packing fraction of metal powder is increased to increase coil inductance, then the magnetic permeability improves, but the DC superposition characteristics are degraded
Solution Approach 1:
Different grain diameter metal powders are distributed throughout the magnetic metal powder containing resin to create local variations in packing density and contact characteristics. The multi-size distribution ensures that no single region has excessive metal powder contact, thereby maintaining good DC superposition characteristics while achieving high overall inductance through increased magnetic permeability.
3Quantity of substance
If metal powder with large grain diameter is used, then the packing fraction can be increased, but the gaps between metal powder particles cannot be effectively filled
Solution Approach 1:
The patent implements a nested structure where smaller grain diameter metal powders (second and third sizes) fill the gaps between larger grain diameter metal powders (first size). This nested arrangement maximizes the packing fraction by utilizing the void spaces that would otherwise be empty, thereby increasing the quantity of magnetic material without causing excessive contact between particles.
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 achieves high magnetic permeability while preventing core loss increase, maintaining magnetic permeability even with decreased packing density, thereby improving coil inductance and DC superposition characteristics.
Implementation Method 1
the magnetic metal powder containing resin includes first metal powder having a first average grain diameter, second metal powder having a second average grain diameter that is smaller than the first average grain diameter, and third metal powder having a third average grain diameter that is smaller than the second average grain diameter
Data Source
AI summary
A coil component 1 is provided with coil conductors 10a and 10b and a magnetic metal powder containing resin 22 (22a and 22b) covering the coil conductors 10a and 10b. The magnetic metal powder containing resin 22 includes first metal powder having a first average grain diameter, second metal powder having a second average grain diameter that is smaller than the first average grain diameter, and third metal powder having a third average grain diameter that is smaller than the second average grain diameter. The first average grain diameter is 15 μm or more and 100 μm or less. The third average grain diameter is 2 μm or less. The first metal powder mainly contains Permalloy and the second and third metal powders mainly contain carbonyl iron.