Magnetic Paste Composition for Printability and Magnetic Permeability

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Solution Overview

Problem

Magnetic pastes containing high amounts of magnetic powder exhibit increased viscosity, leading to poor printability, while also compromising the mechanical strength and relative magnetic permeability of the cured products.

Innovation Solution

Incorporating a dispersant with a polyester skeleton into the magnetic paste reduces its viscosity, enhances printability, and maintains or improves the relative magnetic permeability and mechanical strength of the cured product.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic powder is added to enhance relative magnetic permeability, then the relative magnetic permeability of the cured product is improved, but the viscosity of the paste increases and printability deteriorates

Engineering Contradiction:
Improverelative magnetic permeabilityVSAvoidprintability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

A dispersant with a polyester skeleton is introduced as an intermediary substance to mediate between magnetic powder particles and the resin matrix. The dispersant adsorbs onto magnetic powder surfaces, providing steric or electrostatic repulsion that prevents aggregation and reduces paste viscosity, thereby maintaining printability while allowing high magnetic powder content for enhanced relative magnetic permeability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The chemical structure parameters of the dispersant are specifically optimized by selecting compounds with a polyester skeleton and controlling the ratio of ester bonds to other bonds (0.3 or more). This parameter change in the dispersant structure enables effective reduction of magnetic powder aggregation at high concentrations, simultaneously achieving low viscosity for good printability and high relative magnetic permeability in the cured product

Inventive Principle:
Principle #35Parameter changes

2Reliability

If magnetic powder is added to enhance relative magnetic permeability, then the relative magnetic permeability of the cured product is improved, but the mechanical strength of the cured product deteriorates

Engineering Contradiction:
Improverelative magnetic permeabilityVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The dispersant acts as a bonding intermediary between magnetic powder particles and the resin matrix, creating strong interfacial adhesion. The polyester skeleton of the dispersant forms a cohesive network that distributes stress effectively, preventing crack propagation and maintaining mechanical strength even at high magnetic powder loadings that would otherwise compromise the cured product structure

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite material system consisting of magnetic powder, resin, and dispersant where the dispersant forms a continuous phase that binds the magnetic powder particles together. This composite structure with optimized phase distribution and interfacial bonding achieves both high relative magnetic permeability and maintained mechanical strength through synergistic material combination

Inventive Principle:
Principle #40Composite materials

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 use of a magnetic paste with a dispersant having a polyester skeleton achieves a balance between high relative magnetic permeability and excellent printability, resulting in a cured product with enhanced mechanical strength and reduced magnetic loss.

Implementation Method 1

a magnetic paste containing a dispersant having a polyester skeleton... the viscosity of the paste was lowered

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

a filling resin containing magnetic substance particles, such as ferric oxide (III) or cobalt ferrite... relative magnetic permeability of the cured product was enhanced

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentEP3985691B1Use of magnetic paste, circuit board, and method of its production
Publication Date: 2025.01.22 AJINOMOTO CO INC
  • EP3985691B1 patent drawingFigure 1~2
  • EP3985691B1 patent drawingFigure 3~4
  • EP3985691B1 patent drawingFigure 5~6

AI summary

Provided is a magnetic paste containing: magnetic powder (A); an epoxy resin (B); a dispersant (C); and a curing agent (D), in which the component (C) has a polyester skeleton represented by the following formula (1) . (In the formula (1), R is independently a divalent hydrocarbon group having 2 to 10 carbon atoms, and n is an integer of 2 to 1,000.)