Ti-Al-N Thermistor Sensor with Ti-N Bonding Layer
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Solution Overview
Problem
Conventional thermistor sensors face challenges in achieving high reliability and heat resistance, particularly when using Ti—Al—N thermistor materials, as they require high-temperature firing and have issues with electrode bonding and fragility of thin ceramic substrates, limiting the development of flexible, thin-film thermistor sensors.
Innovation Solution
A temperature sensor design featuring a Ti—Al—N thermistor material with a Ti—N bonding layer and noble metal electrodes, deposited on an insulation film substrate, which enhances bondability and heat resistance without the need for high-temperature firing, allowing for a flexible and reliable thin-film thermistor sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Cr or Ni-Cr bonding layer is deposited to improve bondability of noble metal electrodes to Ti-Al-N thermistor material, then electrode bonding is enhanced, but the bonding layer oxidizes at high temperatures causing resistance increase and reliability degradation
Solution Approach 1:
The patent introduces a Ti-N bonding layer as an intermediary between the Ti-Al-N thermistor material and the noble metal electrode. This Ti-N layer serves as a mediator that provides both good bondability to the Ti-Al-N material and high oxidation resistance, eliminating the need for Cr or Ni-Cr bonding layers that are prone to oxidation.
Solution Approach 2:
The patent changes the material parameter of the bonding layer from Cr or Ni-Cr to Ti-N, which fundamentally alters the chemical properties. The Ti-N bonding layer has lower oxidation tendency compared to Cr-based materials, thereby resolving the oxidation issue while maintaining good bondability through nitride-nitride interface compatibility.
2Length of moving object
If ceramic substrate is thinned to achieve very thin thermistor sensor, then sensor thickness is reduced, but substrate becomes fragile and breaks easily
Solution Approach 1:
The patent transitions from rigid ceramic substrates to flexible film substrates for supporting the Ti-Al-N thermistor material. This allows the sensor to be made very thin while maintaining flexibility and resistance to breakage, as films can be thinned without becoming brittle like ceramics.
3Stability of the object's composition
If high-temperature firing is performed to achieve stable thermistor characteristic, then thermistor property stability is improved, but resin film substrate cannot withstand the temperature
Solution Approach 1:
The patent changes the material system from oxide-based thermistor materials requiring high-temperature firing to nitride-based Ti-Al-N materials that can be deposited as thin films at lower temperatures. This parameter change in material composition allows compatibility with resin film substrates while achieving stable thermistor characteristics through the nitride material's inherent properties.
Solution Approach 2:
The patent replaces the thermal processing mechanism (high-temperature firing) with a deposition mechanism (sputtering or similar thin-film deposition). Instead of using heat to stabilize the thermistor material, the nitride-based material is deposited directly in a stable configuration that does not require subsequent high-temperature treatment, thereby protecting the temperature-sensitive resin film substrate.
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 provides a high-reliability, flexible temperature sensor with improved heat resistance and stability, enabling the production of thin-film thermistor sensors that can be bent and placed on curved surfaces without separation, while maintaining a high B constant and thermistor characteristics.
Implementation Method 1
a thin film thermistor portion (3) made of a Ti-Al-N thermistor material
Implementation Method 2
the pair of pattern electrodes has a Ti-N bonding layer (5) formed on the thin film thermistor portion (3)
Data Source
AI summary
Provided are a temperature sensor that is hard to increase resistance in the electrode structure with respect to a Ti—Al—N thermistor material layer even under a high-temperature environment, and has a high reliability with a high heat resistance as well as a method for producing the same. The temperature sensor includes an insulation substrate; a thin film thermistor portion formed on the insulation substrate; and a pair of pattern electrodes formed on the insulation substrate with a pair of opposed electrode portions being arranged so as to be opposed to each other on the thin film thermistor portion, wherein the thin film thermistor portion is made of a Ti—Al—N thermistor material, and the pair of pattern electrodes has a Ti—N bonding layer formed on the thin film thermistor portion and an electrode layer made of a noble metal formed on the bonding layer.