Resin Composition Magnetic Powder Particle Size Optimization

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Solution Overview

Problem

There is a limit to improving the relative permeability of magnetic materials by increasing the filling rate of magnetic powder, which also compromises the mechanical strength, leading to production stability issues in inductor elements.

Innovation Solution

A resin composition incorporating a ferrite powder with an average particle diameter of 0.8 µm or less and a magnetic powder with an average diameter of 1.5 µm or more, within a specific volume ratio, is used to achieve superior mechanical strength and relative permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If the filling rate of magnetic powder is increased to improve relative permeability, then the magnetic characteristics are enhanced, but the mechanical strength deteriorates and cracks occur

Engineering Contradiction:
Improverelative permeabilityVSAvoidmechanical strength
Core Design Contradiction:
Duration of action of moving objectVSStrength

Solution Approach 1:

The patent applies parameter changes by controlling the average particle diameter of magnetic powder within a specific range (0.5 µm to 5.0 µm) and optimizing the filling rate (60-80 vol%). This parameter optimization allows achieving high relative permeability (μ'≥10.0 at 100 MHz) while maintaining adequate mechanical strength, resolving the contradiction between magnetic performance and structural integrity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining magnetic powder with specific resin components (epoxy resin, phenolic resin, or polyester resin) in a formulated resin composition. This composite approach enables the cured product to simultaneously achieve enhanced magnetic characteristics and improved mechanical properties, including resistance to cracking, by leveraging the synergistic effects of the material combination

Inventive Principle:
Principle #40Composite materials

2Duration of action of moving object

If the filling rate of magnetic powder is increased to improve relative permeability, then the magnetic characteristics are enhanced, but production stability deteriorates

Engineering Contradiction:
Improverelative permeabilityVSAvoidproduction stability
Core Design Contradiction:
Duration of action of moving objectVSReliability

Solution Approach 1:

The patent optimizes particle diameter parameters (0.5 µm to 5.0 µm) and filling rate (60-80 vol%) to achieve a balance point where high relative permeability is obtained without compromising production stability. This controlled parameter range prevents excessive cracking and ensures consistent manufacturing quality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by ensuring uniform distribution of magnetic powder particles within the resin composition through proper formulation. This uniform local distribution prevents localized stress concentrations and cracking, thereby maintaining production stability while achieving high overall magnetic performance

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3917290A1Resin composition
Publication Date: 2021.12.01 AJINOMOTO CO INC
  • EP3917290A1 patent drawingFigure 1~2
  • EP3917290A1 patent drawingFigure 3~4
  • EP3917290A1 patent drawingFigure 5~6

AI summary

Provided is a resin composition including (A) a magnetic powder and (B) a thermosetting resin, in which the (A) component includes (A-1) a ferrite powder having an average particle diameter of 0.8 pm or less and (A-2) a magnetic powder having an average particle diameter of 1.5 pm or more; and a volume ratio of the (A-2) component to the (A-1) component ((A-2) component/(A-1) component) is in the range of 0.8 to 34.0.