Powder Magnetic Core Terminals With Oxide Layers for Insulation
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Solution Overview
Problem
Existing powder magnetic cores with metallic magnetic materials face challenges in achieving sufficient insulation between terminals and adequate adhesion strength due to the limitations of oxide thickness and conductor film adhesion, which affect magnetic properties and reliability in high-temperature environments.
Innovation Solution
A powder magnetic core with terminals formed using Fe-based alloy particles, where an underlayer of Cr or Al oxide is deposited on the surface, followed by a first layer of Cr or Al oxide and a second layer of conductive materials like Au, Ag, or Cu, with a third layer of Ni, Au, Ag, or Sn, enhancing insulation and adhesion through specific layer thickness relationships and deposition methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the oxide film is increased to improve insulation between terminals, then the insulation resistance is improved, but the magnetic permeability is lowered due to the grain boundary phase acting as magnetic gaps
Solution Approach 1:
The oxide film is segmented into multiple layers with different functions: a first oxide layer (50-150 nm) for insulation and a second oxide layer (150-300 nm) for adhesion. This segmentation allows each layer to optimize its thickness for its specific function, preventing the magnetic permeability degradation that would occur with a single thick oxide layer while ensuring sufficient insulation resistance.
Solution Approach 2:
Different regions of the oxide film structure are given different properties: the first oxide layer has lower thickness optimized for insulation without excessive magnetic gap formation, while the second oxide layer has higher thickness optimized for adhesion strength. This local differentiation of quality allows simultaneous optimization of insulation and magnetic properties.
2Ease of manufacture
If a conductor film is directly formed on the surface of the powder magnetic core to create terminals, then the manufacturing process is simplified, but the adhesion strength is insufficient
Solution Approach 1:
The patent introduces a second oxide layer as an intermediary between the substrate and the conductor film. This intermediate layer acts as a bonding bridge that significantly improves adhesion strength compared to direct conductor film formation, while still maintaining a relatively simple manufacturing process using conventional sputtering or evaporation methods.
3Reliability
If the heat treatment temperature is elevated to increase oxide film thickness for insulation, then the insulation resistance is improved, but pure iron forms in the film which inhibits high resistance
Solution Approach 1:
The patent changes the parameter of oxide layer thickness distribution by using a two-layer structure with specific thickness ranges. The first layer is kept thin (50-150 nm) to prevent pure iron formation and maintain high resistance, while the second layer is thicker (150-300 nm) for adhesion. This parameter control achieves insulation improvement without the harmful effects of excessive thickness or pure iron formation.
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 provides improved insulation and increased terminal adhesion strength, maintaining magnetic properties and reliability even in high-temperature environments, while allowing for efficient manufacturing processes.
Implementation Method 1
each of particles is oxidized at high temperature in the state of a green compact to bond the particles with oxides formed on the surface as a grain boundary phase, and to cover the surface of the powder magnetic core with a thin film of the oxide
Implementation Method 2
a conductor film is directly formed as a terminal on the surface of the powder magnetic core by a sputtering method
Implementation Method 3
a conductor film is directly formed as a terminal on the surface of the powder magnetic core by a sputtering method, an ion plating method
Data Source
AI summary
A powder magnetic core with terminal includes: a powder magnetic core composed of Fe-based alloy particles including Fe and an element M (M is Cr and/or Al) which is more easily oxidizable than Fe; and at least two terminals formed at an interval on a surface of the powder magnetic core. The powder magnetic core includes the Fe-based alloy particles, and an underlayer including the element M (M is Cr and/or Al), Fe and O formed on a surface of the Fe-based alloy particles. A first layer including at least one of Cr or Al and O is formed on a surface including a region in which the terminals of the powder magnetic core are formed. The terminals are formed on a surface of the first layer. Each of the terminals includes a second layer including one of Au, Ag, Cu, Ti or Cr.