Voltage Nonlinear Resistor Ceramic with Strontium Titanate
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Solution Overview
Problem
Conventional voltage nonlinear resistor ceramics face challenges in achieving good varistor characteristics and moisture resistance, especially when used in smaller and thinner forms required for advanced electronic components like in-vehicle components.
Innovation Solution
A voltage nonlinear resistor ceramic composition comprising Zn oxide, Co oxide, R oxide, M1 oxide, M2 oxide, and strontium titanate, with specific mole ratios, which suppresses grain growth during sintering, enhances anti-ESD characteristics, and improves moisture resistance by using strontium titanate instead of barium titanate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the interlayer thickness is reduced to achieve smaller and thinner varistor, then the size of the varistor is reduced, but it becomes difficult to obtain good varistor characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the voltage nonlinear resistor ceramic by incorporating specific amounts of Cr oxide (0.01-2 mole portion), M1 oxide (0.10-5 mole portion), M2 oxide (0.0005-5 mole portion), and strontium titanate (0.10-5 mole portion) alongside Zn oxide and Co oxide. This compositional parameter change enables achieving good varistor characteristics even with reduced interlayer thickness, resolving the contradiction between miniaturization and performance maintenance.
2Reliability
If barium titanate is used to achieve good varistor characteristics, then the varistor characteristics are improved, but moisture resistance deteriorates
Solution Approach 1:
The patent extracts barium titanate from the composition and replaces it with strontium titanate. By removing the harmful component (barium titanate that causes poor moisture resistance) and substituting it with a beneficial alternative (strontium titanate that provides both good varistor characteristics and improved moisture resistance), the contradiction between varistor characteristics and moisture resistance is resolved.
3Manufacturing precision
If Cr oxide is added to suppress grain growth during sintering, then grain growth is suppressed and varistor characteristics are improved, but the complexity of composition increases
Solution Approach 1:
The patent merges multiple functions into a single compositional system by combining Cr oxide (for grain growth suppression), M1 oxide and M2 oxide (for additional performance enhancement), and strontium titanate (for both varistor characteristics and moisture resistance) with the base Zn oxide-Co oxide system. This integrated approach achieves comprehensive performance improvement while managing composition complexity through synergistic interactions among the additives.
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 ceramic composition achieves excellent varistor characteristics, including high ESD withstand capability and low leakage current, while maintaining superior moisture resistance, even in high-humidity environments, making it suitable for in-vehicle components.
Implementation Method 1
by including a specific amount of strontium titanate, grain growth of crystal grain during sintering can be suppressed
Implementation Method 2
A varistor as one example of an electronic component having a voltage nonlinear resistor layer is used to protect IC circuits of electronic devices and so on by absorbing or removing an external surge (abnormal voltage), such as static electricity, or noise
Data Source
AI summary
A voltage nonlinear resistor ceramic comprises: a Zn oxide; a Co oxide; an R (specific rare earth) oxide; a Cr oxide; an M1 (Ca, Sr) oxide; an M2 (Al, Ga, In) oxide; and strontium titanate. When content of the Zn oxide is assumed to be 100 mole portion in terms of Zn, content of the Co oxide is 0.30 to 10 mole portion in terms of Co, content of the R oxide is 0.10 to 10 mole portion in terms of R, content of the Cr oxide is 0.01 to 2 mole portion in terms of Cr, content of the M1 oxide is 0.10 to 5 mole portion in terms of M1, content of the M2 oxide is 0.0005 to 5 mole portion in terms of M2, and content of the strontium titanate is 0.10 to 5 mole portion in terms of SrTiO3.