Molded Body Fixing Strength via Electrode Surface Pits
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Solution Overview
Problem
Conventional magnetic mold materials with high magnetic powder content suffer from reduced fixing strength between the magnetic mold material and external electrodes due to decreased resin contact, leading to potential electrode detachment in electronic parts like mold coils.
Innovation Solution
A molded body is created using a magnetic mold material with at least 65 vol % magnetic powder and up to 35 vol % resin, where the external electrode features pits and projections with spacing smaller than the maximum particle size of the magnetic powder, ensuring resin contact and enhancing fixing strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the proportion of magnetic powder in the magnetic mold material is increased to improve magnetic properties, then the magnetic permeability is improved, but the proportion of resin is decreased, resulting in insufficient contact between resin and external electrode surface, which deteriorates the fixing strength
Solution Approach 1:
The external electrode surface is designed with a porous structure comprising pits and projections. The spacing between pits and projections is controlled to be smaller than the maximum particle size of magnetic powder but sufficient to allow resin penetration. This porous structure increases the surface area for resin contact while maintaining high magnetic powder content (65 vol % or more) in the magnetic mold material, thereby resolving the contradiction between magnetic permeability and fixing strength
Solution Approach 2:
The surface of the external electrode is given non-uniform local structure with pits and projections rather than a flat surface. This local quality change creates regions of varying resin accessibility, ensuring that resin can effectively contact and adhere to the electrode surface even when the overall resin proportion in the magnetic mold material is reduced to 35 vol % or less
Data Source
AI summary
There is provided a molded body having high fixing strength between a magnetic mold material and an external electrode. The molded body uses the magnetic mold material comprising at least 65 vol % of magnetic powder and up to 35 vol % of resin and the external electrode that has pits and projections on a surface that makes contact with the magnetic mold material. The external electrode and the magnetic mold material are integrally-molded such that at least a portion of the external electrode is exposed at at least one surface of the molded body. Spacing between the pit and projection of the external electrode is smaller than the maximum particle size of the magnetic powder.