Powder-Core Inductor Molding for High Permeability and Insulation
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Solution Overview
Problem
Existing power inductors face challenges in achieving high magnetic permeability and reliability due to issues such as low saturation magnetic flux density, air gaps, and high DC resistance, which hinder miniaturization and increase production complexity.
Innovation Solution
The development of an inductor with a magnetic core made of soft magnetic powder containing more than 50 wt % spherical particles, integrated with a wire coil through co-firing/integrated molding at a molding pressure of 12–24 T/cm2, which enhances magnetic permeability and insulation resistance while simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If molding pressure is increased to improve magnetic core density and initial magnetic permeability, then magnetic properties are improved, but wire insulation is damaged causing low insulation resistance or short circuit
Solution Approach 1:
The patent changes the particle morphology parameter of the magnetic powder from irregular shape to spherical shape. This parameter change allows the magnetic powder to be densely packed around the wire coil under high molding pressure without damaging the wire insulation, achieving both high initial magnetic permeability (>40) and high insulation resistance (>100MΩ) simultaneously
Solution Approach 2:
The patent uses spherical magnetic powder particles that can be densely packed while maintaining a controlled porous structure in the magnetic core. This porous structure reduces the molding pressure needed to achieve high density, preventing wire insulation damage while maintaining high magnetic permeability
2Device complexity
If wire-wound type is used to achieve simple structure, then device complexity is reduced, but saturation magnetic flux density is low and miniaturization is hindered
Solution Approach 1:
The patent merges the magnetic core and wire coil into a single integrated component through one-step molding. The wire coil is embedded directly into the magnetic core during the molding process, eliminating the need for separate assembly steps and reducing the overall inductor volume while maintaining structural simplicity
Solution Approach 2:
The patent uses composite material consisting of spherical magnetic powder particles and binding agent to form the magnetic core. This composite material allows for high saturation magnetic flux density and enables miniaturization while maintaining structural integrity and simplicity
3Ease of manufacture
If integrated molding is used to simplify manufacturing process, then ease of manufacture is improved, but production efficiency is reduced due to low molding pressure requirements
Solution Approach 1:
The patent changes the particle morphology parameter to spherical shape, which enables the use of high molding pressure (10-50 MPa) in the integrated molding process. This parameter change increases the density of the magnetic core and allows for faster molding cycles, thereby improving production efficiency while maintaining process simplicity
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 proposed inductor achieves high initial magnetic permeability (>40), reduced DC resistance, and improved insulation withstand voltage, enabling a smaller, thinner, and more reliable power inductor with enhanced electromagnetic properties and production efficiency.
Implementation Method 1
The inductor components are made by integrated molding at a molding pressure of 12 ̃24 T/cm2
Implementation Method 2
an annealing step, placing the raw inductor in a heat furnace for calcinating and annealing so as to release residual stress inside the magnetic core
Data Source
AI summary
An inductor provided in the present invention, includes a magnetic core made of soft magnetic powder and a wire coil embedded inside the magnetic core. A method for manufacturing the inductor includes steps of: a pressing and molding step; and an annealing step. At the pressing and molding step, placing a wire coil in a mold, filling a cavity of the mold with soft magnetic powder surrounding the wire coil, molding at a pressure of 12˜24 T/cm2 to obtain a raw inductor. At the annealing step, placing the raw inductor in a heat furnace for calcinating and annealing so as to release residual stress inside the magnetic core and obtain the integrated inductor. In the present invention, a high-density, high-permeability inductor can be obtained, and no need to limit powder particle size of the soft magnetic powder.