Ferrite Sintered Sheet Composition for Low Magnetic Loss
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Solution Overview
Problem
Ferrite sintered sheets used in communication equipment, such as cellular phones, face challenges in enhancing communication sensitivity due to high magnetic permeability losses, breakage during handling, and temperature-dependent changes in magnetic properties, which affect the antenna's performance and durability.
Innovation Solution
A ferrite sintered sheet with a composition of 47.5 to 49.8 mol% Fe2O3, 13.5 to 19.5 mol% NiO, 21 to 27 mol% ZnO, 7.5 to 12.5 mol% CuO, and 0.2 to 0.8 mol% CoO, along with 0.2 to 1.4% SnO2 and 0.005 to 0.03% S by weight, achieving a high sintered density and controlled magnetic permeability values, is developed, with optional adhesive and protective layers and surface grooves for improved handling and attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the real part of magnetic permeability (μ′) is increased to enhance communication sensitivity, then the inductance of the antenna increases, but the imaginary part (μ′′) representing loss becomes larger, causing deterioration in communication sensitivity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the ferrite material. Specifically, it uses Ni-Zn-Cu-Co ferrite with controlled oxidation during sintering to achieve a specific magnetic permeability parameter profile where μ′ is maximized while μ′′ is minimized, resolving the contradiction between inductance enhancement and loss reduction
Solution Approach 2:
The patent employs composite materials by creating a multi-element ferrite system (Ni-Zn-Cu-Co ferrite) rather than using simple ferrite. This composite composition allows for optimized magnetic properties where the interaction between different metal elements produces a material with high μ′ and low μ′′, simultaneously achieving high inductance and low loss
2Shape
If the ferrite sintered sheet has a microfine structure with voids to control grain growth, then the structure is formed, but the sheet readily suffers from breakage upon handling
Solution Approach 1:
The patent applies parameter changes by controlling the sintering temperature parameter to achieve complete densification. By sintering at 900-960°C for 2-180 minutes, the material achieves high density (5.0-5.3 g/cm³) which eliminates voids and simultaneously provides the desired microfine structure with adequate grain size, while also achieving high mechanical strength that prevents breakage during handling
3Strength
If the ferrite sintered sheet has high sintered density to prevent breakage, then mechanical strength increases, but the production process becomes more difficult due to longer sintering time required
Solution Approach 1:
The patent applies parameter changes by optimizing the sintering temperature parameter to a specific range (900-960°C). This temperature range is high enough to achieve rapid densification and high mechanical strength, but controlled to manage production efficiency. The specific composition parameters of Ni-Zn-Cu-Co ferrite are also optimized to enable complete sintering within 2-180 minutes, balancing strength achievement with production time
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 ferrite sintered sheet achieves a large real part magnetic permeability value, low imaginary part value, and minimal temperature-dependent changes, enhancing communication sensitivity and stability while preventing breakage during handling.
Implementation Method 1
the ferrite sintered sheet having a microfine structure constituted of crystal grains and voids which is in the course of grain growth
Implementation Method 2
a magnetic permeability of the ferrite sintered sheet is controlled by adding CoO to Ni—Zn—Cu ferrite
Implementation Method 3
as the μ′ of the magnetic permeability of the ferrite sintered sheet increases, a loss represented by an imaginary part (μ′) of the magnetic permeability of the ferrite sintered sheet becomes larger
Data Source
AI summary
An object or technical task of the present invention is to provide a ferrite sintered sheet having a dense ferrite microfine structure which has a large μ′ value, a small μ″ value, and a small temperature-dependent change of the μ′ value thereof. The present invention relates to a ferrite ceramics having a composition comprising 47.5 to 49.8 mol % of Fe2O3, 13.5 to 19.5 mol % of NiO, 21 to 27 mol % of ZnO, 7.5 to 12.5 mol % of CuO and 0.2 to 0.8 mol % of CoO, all of the molar amounts being calculated in terms of the respective oxides, the ferrite ceramics further comprising 0.2 to 1.4% by weight of SnO2 and 0.005 to 0.03% by weight of S and having a density of 5.05 to 5.30 g/cm3; and a ferrite sintered sheet comprising the ferrite sintered plate on a surface of which a groove or grooves are formed, and an adhesive layer and/or a protective layer formed on the ferrite sintered plate.