Mn-Zn Ferrite Magnetic Core Composition for Thermal Shock Reliability
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Solution Overview
Problem
Magnetic cores used in vehicle power electronics face challenges in reliability, particularly in low-temperature characteristics and thermal shock, due to their small size and limited heat dissipation capabilities, which affect their performance in vehicle environments.
Innovation Solution
The magnetic core composition is optimized by increasing the content of main composition materials at the grain boundary, using a post-addition process where additives like cobalt oxide, nickel oxide, and non-magnetic additives such as silicon oxide and calcium oxide are introduced after calcination, to enhance reliability and thermal shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the magnetic core is slimmed down to reduce size, then the device compactness is improved, but the heat dissipation capability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the ferrite material by adding specific amounts of CoO (0.1-1.0 wt%), NiO (0.1-0.5 wt%), and other oxides to the base composition of Fe2O3 (65-75 wt%), MnO (15-30 wt%), and ZnO (5-15 wt%). These compositional parameter changes improve the material's intrinsic heat dissipation properties and thermal stability, allowing the slimmed magnetic core to maintain adequate heat dissipation capability despite its reduced size.
2Ease of manufacture
If conventional ferrite composition is used, then the manufacturing process is simple, but the low-temperature characteristics and thermal shock resistance deteriorate
Solution Approach 1:
The patent applies preliminary action by adding CoO and NiO after the calcination step rather than mixing all components from the beginning. The base ferrite composition (Fe2O3, MnO, ZnO) is first calcined to form the core ferrite structure, and then CoO and NiO are added to the calcined powder before final sintering. This preliminary action allows the base structure to form first, ensuring proper ferrite phase development, and then the cobalt and nickel are incorporated to enhance low-temperature characteristics and thermal shock resistance without disrupting the fundamental manufacturing simplicity.
3Volume of moving object
If the magnetic core size is reduced for slimming, then the device compactness is improved, but the heat capacity and heat dissipation surface area deteriorate
Solution Approach 1:
The patent changes the material composition parameters to compensate for the reduced size effects. By incorporating CoO (0.1-1.0 wt%) and NiO (0.1-0.5 wt%) into the ferrite matrix alongside the base composition of Fe2O3 (65-75 wt%), MnO (15-30 wt%), and ZnO (5-15 wt%), the material's thermal properties are enhanced. These compositional changes improve heat capacity and thermal conductivity at the material level, allowing the smaller magnetic core to maintain adequate heat dissipation performance despite having reduced overall volume and surface area.
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 optimized magnetic core exhibits improved low-temperature characteristics and thermal shock resistance, meeting AEC-Q200 reliability standards with reduced core loss and permeability changes, ensuring stability under various vehicle environmental conditions.
Implementation Method 1
the proportion of a specific metal element at a grain boundary can be increased so that the magnetic core can exhibit better reliability
Implementation Method 2
slimmed magnetic elements have relatively small size and surface area, which are disadvantageous from the aspects of heat capacity and heat dissipation
Data Source
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AI summary
Disclosed is a magnetic core having improved reliability. The magnetic core includes 37 to 44 mol% of manganese (Mn), 9 to 16 mol% of zinc (Zn), 42 to 52 mol% of iron (Fe), a magnetic additive, and a non-magnetic additive, wherein the magnetic core has a permeability of 2,900 or more and a core loss of 500 mW/cm3 or less.