Fe-Cr-Si Alloy Coil Component Oxide Film Insulation
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Solution Overview
Problem
The challenge is to enhance the volume resistivity of Fe—Cr—Si alloy grains in coil components to maintain high saturated magnetic flux density and prevent current leakage, which is not adequately addressed by conventional ferrites, especially when the magnetic body contains a glass component that reduces the volume ratio of Fe—Cr—Si alloy grains.
Innovation Solution
A coil component with a magnetic body composed of Fe—Cr—Si alloy grains, where the grains have an oxide film acting as an insulation layer, allowing them to bond directly and with the coil, ensuring high volume resistivity without a glass component, thus maintaining high saturated magnetic flux density and preventing current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Fe—Cr—Si alloy grains are used as the magnetic body to increase saturated magnetic flux density, then the electrical current amplification is improved, but the volume resistivity decreases causing current leakage from the coil to the magnetic body
Solution Approach 1:
An oxide film is introduced as an intermediary insulating layer on the surface of Fe—Cr—Si alloy grains. This oxide film acts as a mediator that electrically isolates the coil from the magnetic body while allowing magnetic flux to pass through, thereby preventing current leakage without compromising the high saturated magnetic flux density of the alloy grains.
Solution Approach 2:
The surface properties of Fe—Cr—Si alloy grains are modified by forming an oxide film through controlled oxidation. This parameter change transforms the surface from conductive to insulating, increasing the volume resistivity of the magnetic body while preserving the bulk magnetic properties of the alloy grains.
2Ease of manufacture
If a glass component is added to the magnetic paste to improve manufacturability, then the ease of manufacture is improved, but the volume ratio of Fe—Cr—Si alloy grains decreases lowering the saturated magnetic flux density
Solution Approach 1:
The glass component is extracted (removed) from the magnetic paste formulation. By eliminating the glass component entirely, the volume ratio of Fe—Cr—Si alloy grains is maximized, ensuring high saturated magnetic flux density while the oxide film provides the necessary insulation and binding functions previously served by glass.
3Reliability
If the oxide film thickness is increased to improve insulation, then the volume resistivity is improved, but the magnetic alloy grain bonding is weakened reducing mechanical strength
Solution Approach 1:
The oxide film thickness is optimized to a specific range (0.01 to 0.5 μm) to achieve the optimal balance between insulation and bonding. This parameter optimization ensures sufficient volume resistivity while maintaining adequate mechanical strength through controlled oxidation conditions.
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
This approach effectively increases the saturated magnetic flux density and prevents inductance drop, meeting the demand for electrical current amplification while ensuring high volume resistivity and stable magnetic performance.
Implementation Method 1
an oxide film is present on the surface of each magnetic alloy grain... the oxide film acts as an insulation layer, allowing them to bond directly and with the coil, ensuring high volume resistivity
Implementation Method 2
an oxide film is present on the surface of each magnetic alloy grain... allowing them to bond directly and with the coil
Data Source
AI summary
A coil component is of the type where a helical coil is directly contacting a magnetic body, which is still capable of meeting the demand for electrical current amplification. A coil component, comprising a magnetic body mainly constituted by magnetic alloy grains, and a coil formed on the magnetic body; wherein an oxide film of the magnetic alloy grains is present on the surface of each of the magnetic alloy grains, and based on grain size by volume standard, the magnetic alloy grains have a d50 in a range of 3.0 to 20.0 μm, d10/d50 in a range of 0.1 to 0.7, and d90/d50 in a range of 1.4 to 5.0.