Soft Magnetic Sheet Lamination for Humidity Stability
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Solution Overview
Problem
Conventional methods for producing soft magnetic sheets, such as kneading and rolling, or coating, face challenges in maintaining magnetic permeability and sheet thickness stability, especially under high-temperature or high-humidity environments, leading to decreased magnetic properties and uneven thickness.
Innovation Solution
A sheet-like soft magnetic material composed of a mixture of flat soft magnetic powder, acrylic rubber with a glycidyl group, epoxy resin, curing agent, and solvent, where the powder is arranged in the in-plane direction, and the composition is laminated and compressed without rolling to enhance cohesive force, heat resistance, and humidity resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a kneading and rolling method is used to produce soft magnetic sheets, then high density filling of soft magnetic powder and easy thickness adjustment are achieved, but strain occurs in the soft magnetic powder during kneading causing deterioration of magnetic properties and increased sheet thickness under high temperature or high humidity environments
Solution Approach 1:
The invention divides the soft magnetic sheet into a laminate structure consisting of multiple thin soft magnetic sheets bonded together. Each thin sheet is produced by coating method without kneading, avoiding strain on the soft magnetic powder. The laminate structure achieves the desired thickness while maintaining magnetic properties, as each layer is independently formed without mechanical deformation.
Solution Approach 2:
The invention uses a composite binder system comprising both a rubber component and a resin component in specific weight ratios (rubber: 10-50 parts, resin: 50-90 parts based on 100 parts of soft magnetic powder). This composite binder provides both adhesion between layers and dimensional stability, preventing sheet thickness increase under high temperature and humidity while maintaining magnetic permeability.
2Reliability
If a coating method is used to produce soft magnetic sheets, then strain in soft magnetic powder is minimized and sheet thickness change is reduced, but it is not suited for producing relatively thick soft magnetic sheets due to unevenness in coating thickness and difficulty in drying
Solution Approach 1:
The invention divides the soft magnetic sheet into a laminate structure consisting of multiple thin soft magnetic sheets bonded together. Each thin sheet is produced by coating method without kneading, avoiding strain on the soft magnetic powder. The laminate structure achieves the desired thickness while maintaining magnetic properties, as each layer is independently formed without mechanical deformation.
3Manufacturing precision
If multiple thin curable soft magnetic sheets are laminated to produce a laminate-type soft magnetic sheet, then the sheet thickness change of individual sheets is small, but the laminated sheet becomes thicker under high temperature or high humidity environment causing magnetic permeability to decrease
Solution Approach 1:
The invention uses a composite binder system comprising both a rubber component and a resin component in specific weight ratios (rubber: 10-50 parts, resin: 50-90 parts based on 100 parts of soft magnetic powder). This composite binder provides both adhesion between layers and dimensional stability, preventing sheet thickness increase under high temperature and humidity while maintaining magnetic permeability.
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 solution achieves stable magnetic properties and minimal thickness change even under harsh environmental conditions, maintaining high magnetic permeability and dimensional stability, suitable for use in electronic devices and RFID systems.
Implementation Method 1
an acrylic rubber, an epoxy resin, a curing agent for the epoxy resin... the acrylic rubber has a glycidyl group
Implementation Method 2
the flat soft magnetic powder is arranged in an in-plane direction of the sheet-like soft magnetic material
Implementation Method 3
compressing the laminate at a temperature at which a curing reaction occurs without rolling the laminate
Data Source
AI summary
The present invention is to impart, to a sheet-like soft magnetic material, a configuration in which sheet thickness change is suppressed and in which fluctuation in magnetic permeability is small even under a high-temperature or a high-temperature, high-humidity environment, even when a plurality of thin curable soft magnetic sheets produced by a coating method are laminated. The sheet-like soft magnetic material is formed from a soft magnetic composition which is formed by mixing at least a flat soft magnetic powder, an acrylic rubber, an epoxy resin, a curing agent for the epoxy resin, and a solvent. The flat soft magnetic powder is arranged in an in-plane direction of the sheet-like soft magnetic material. An acrylic rubber having a glycidyl group is used for the acrylic rubber. The weight ratio of the flat soft magnetic powder with respect to the total amount of the acrylic rubber, the epoxy resin, and the curing agent for the epoxy resin is 3.7 to 5.8.