Alumina Temperature Sensor Bridge Layout for Thermal Expansion Mismatch
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Solution Overview
Problem
Existing temperature sensors face a decline in detection accuracy due to the difference in thermal expansion coefficients between the substrate and resistive portions, leading to uneven surface roughness and reduced adhesion.
Innovation Solution
A temperature sensor design featuring an alumina substrate with a planarization film containing alumina as the main component, where the first and second resistive portions are formed on this film to create a bridge circuit, enhancing adhesion and reducing surface roughness, thus improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a planarization film is formed on the alumina substrate, then surface roughness is reduced and adhesion is improved, but device complexity increases
Solution Approach 1:
An alumina-based planarization film is introduced as an intermediary layer between the alumina substrate and the resistive portions. This mediator layer reduces surface roughness and improves adhesion by providing a compatible thermal expansion coefficient and smooth surface, while maintaining material compatibility through alumina composition.
Solution Approach 2:
The planarization film changes the surface parameters of the substrate by providing a smoother surface topology and modifying the thermal expansion characteristics at the interface. This parameter change enables better adhesion and reduces stress between the substrate and resistive portions without requiring fundamental structural redesign.
2Reliability
If the planarization film contains alumina as main component, then thermal conductivity matching is improved, but manufacturing complexity increases
Solution Approach 1:
The planarization film uses alumina as its main component, matching the substrate material composition. This homogeneity in material composition ensures compatible thermal conductivity and thermal expansion characteristics, improving reliability while simplifying the manufacturing process through material consistency.
Solution Approach 2:
The planarization film is formulated as an alumina-based composite material that combines the thermal properties of alumina with the planarization functionality. This composite approach maintains thermal conductivity matching with the alumina substrate while providing the necessary surface planarization properties.
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 effectively reduces the chances of accuracy decline by ensuring better adhesion and thermal conductivity matching between the substrate and resistive portions, leading to enhanced temperature detection precision.
Implementation Method 1
the difference in thermal expansion coefficients between the substrate and resistive portions, leading to uneven surface roughness and reduced adhesion
Implementation Method 2
The temperature detection device detects a temperature based on the difference in resistance value between the first and second resistors
Data Source
AI summary
A temperature sensor according to the present disclosure includes an alumina substrate, a planarization film, a first resistive portion, and at least one second resistive portion. The planarization film contains alumina as a main component thereof and is formed on the alumina substrate. The first resistive portion is formed on the planarization film. The at least one second resistive portion is formed on the planarization film and forms a bridge circuit along with the first resistive portion.