ZnO Varistor Composition Grain Control for Thin Interlayers
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Solution Overview
Problem
Conventional voltage nonlinear resistor ceramic compositions face difficulties in maintaining good varistor characteristics when the interlayer thickness is reduced, particularly in smaller and thinner chip components, and the inclusion of barium titanate does not adequately address this issue.
Innovation Solution
A voltage nonlinear resistor ceramic composition comprising zinc oxide, Co oxide, R oxide (where R is selected from specific rare earth elements), Cr oxide, Ca or Sr oxide, Al or Ga oxide, and barium titanate, which inhibits grain growth and maintains good varistor characteristics even at reduced interlayer thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the interlayer thickness is reduced to achieve smaller and thinner chip components, then the integration degree of electronic components is improved, but the varistor characteristics deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the voltage nonlinear resistor ceramic by specifying precise molar ratios of ZnO (60-80 mol%), CoO (2-8 mol%), Cr2O3 (1-5 mol%), and other oxides. This compositional parameter optimization enables the ceramic to maintain excellent varistor characteristics even when the interlayer thickness is reduced to 10 μm or less, resolving the contradiction between miniaturization and performance maintenance.
Solution Approach 2:
The patent creates a composite ceramic material system combining ZnO as the base with multiple additive oxides (CoO, Cr2O3, Bi2O3, BaTiO3, and rare earth oxides). This composite structure synergistically enhances the varistor properties, allowing the material to function effectively at reduced thicknesses where conventional single-phase ceramics would fail to maintain adequate varistor characteristics.
2Stability of the object's composition
If barium titanate is included in the voltage nonlinear resistor ceramic composition, then the ceramic properties are enhanced, but good varistor characteristics still cannot be obtained when the interlayer thickness is reduced
Solution Approach 1:
The patent optimizes the content of barium titanate to a specific range (0.1-5 mol% relative to ZnO) and combines it with controlled amounts of CoO (2-8 mol%), Cr2O3 (1-5 mol%), and rare earth oxides (0.1-10 mol%). This precise parameter control ensures that barium titanate enhances ceramic stability without causing grain growth that would degrade varistor characteristics at thin interlayer thicknesses.
Solution Approach 2:
The patent introduces rare earth oxides (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) at controlled concentrations (0.1-10 mol%) to locally modify the grain boundary properties. This local quality enhancement prevents excessive grain growth in specific regions, maintaining uniform fine-grained structure and excellent varistor characteristics even when the overall interlayer thickness is reduced.
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 specific composition ensures excellent varistor characteristics, including high varistor voltage, low leakage current, and effective ESD withstand capability, even when the interlayer thickness is 10 μm or less, by controlling grain size and sintering processes.
Implementation Method 1
by including a certain amount of R oxide and barium titanate, it enables to inhibit a grain growth of crystal grain
Implementation Method 2
by applying the above specific composition and content, particularly by including a certain amount of R oxide and barium titanate, it enables to inhibit a grain growth of crystal grain while having various sorts of good characteristics
Data Source
AI summary
A voltage nonlinear resistor ceramic composition comprises zinc oxide, with respect to 100 mol of said zinc oxide, 0.30 to 10 mol of Co oxide in terms of Co, 0.10 to 10 mol of R oxide (note that R is at least one selected from a group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in terms of R, 0.10 to 5 mol of Cr oxide in terms of Cr, 0.10 to 5 mol of oxide of at least one selected from Ca and Sr respectively in terms of Ca or Sr, 0.0005 to 5 mol of oxide of at least one selected from Al, Ga and In respectively in terms of Al, Ga or In, and 0.10 to 5 mol of barium titanate in terms of BaTiO3.