RuO2-SiO2 Thermistor Interlayer for Stable Low-Resistance Electrodes
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Solution Overview
Problem
Existing thermistor elements face issues with increased resistance values due to peeling of electrodes, inadequate adhesiveness, and the presence of glass layers or air gaps, which lead to instability in electrical characteristics and potential breakage or peeling of the interlayer.
Innovation Solution
A thermistor element with a conductive interlayer formed by uniformly distributing RuO2 grains in contact with each other on the thermistor body, with SiO2 interposing in gaps between the RuO2 grains, and applying these layers using a wet-type application method to achieve high adhesiveness and a thin, low-resistance interlayer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If glass frit is used as a binder in the RuO2 paste, then the paste can be applied to the thermistor body, but glass frit particles intervene between RuO2 grains and increase the resistance value of the interlayer
Solution Approach 1:
The patent extracts and removes the glass frit binder from the RuO2 paste formulation. Instead of using a paste containing glass frit and RuO2 grains, the invention applies only RuO2 grains directly to the thermistor body, eliminating the harmful intermediary substance that causes high resistance and poor adhesion.
Solution Approach 2:
The patent introduces an organic binder as an alternative intermediary substance that does not interfere with electrical conduction. This organic binder enables the RuO2 grains to adhere to the thermistor body without creating the insulating glass frit layers that increase resistance.
2Strength
If a thick film interlayer is formed using high viscosity paste, then the interlayer can be formed, but the amount of RuO2 grains including rare metal increases
Solution Approach 1:
The patent changes the viscosity parameter of the applied material by eliminating glass frit and using only organic binder with RuO2 grains. This parameter change allows the formation of a sufficiently thick interlayer with much lower material quantity, reducing rare metal consumption while maintaining structural integrity.
3Ease of manufacture
If glass layers or air gaps are present in the interlayer, then the interlayer can be formed with binder, but strain or thermal stress is generated due to unevenness
Solution Approach 1:
The patent extracts and eliminates glass layers and air gaps from the interlayer structure by removing the glass frit binder. The resulting interlayer consists solely of RuO2 grains bound with organic binder, creating a uniform structure without scattered glass layers or air gaps that cause stress concentration and adhesion problems.
4Ease of manufacture
If RuO2 grains are not in sufficient contact with each other, then glass frit can be used as binder, but electrical conduction between RuO2 grains is impaired
Solution Approach 1:
The patent removes glass frit from the paste formulation, forcing RuO2 grains to be in direct contact with each other for structural support. This extraction ensures continuous RuO2 grain networks that provide excellent electrical conduction paths while the organic binder maintains adhesion without interfering with conductivity.
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 solution achieves a stable electric characteristic with high adhesiveness between the conductive interlayer and the thermistor body, suppressing the increase in resistance value even under heat cycles, and ensuring the interlayer acts effectively as an auxiliary electrode.
Implementation Method 1
RuO 2 grains in contact with each other are uniformly distributed
Implementation Method 2
SiO 2 interposes in gaps between the RuO 2 grains
Implementation Method 3
the conductive interlayer is formed in a state of being adhered to the thermistor body along the protrusions and the recesses on the surface of the thermistor body
Implementation Method 4
applying these layers using a wet-type application method
Data Source
Figure 1~2
Figure 3A~3C
Figure 4A~4B
AI summary
In a thermistor element, a thermistor body formed of a thermistor material, a conductive interlayer formed on the thermistor body, and an electrode layer formed on the conductive interlayer are provided, the conductive interlayer is formed along protrusions and recesses on a surface of the thermistor body, the conductive interlayer is a layer in which RuO2 grains in contact with each other are uniformly distributed and SiO2 interposes in gaps between the RuO2 grains, and the conductive interlayer is formed in a state of adhering to the thermistor body along the protrusions and the recesses on the surface of the thermistor body.