Flexible Passive Component Structure for CTE-Matched Thin Sensors
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Solution Overview
Problem
Conventional thin-film temperature sensors face issues with mechanical stability and accuracy due to substrate thickness and coefficient of thermal expansion (CTE) mismatches, leading to potential cracking and drift, while polymeric substrates are unsuitable for precise sensors due to shape changes and high CTE.
Innovation Solution
A flexible passive electronic component with a substrate formed from an insulating layer of metal oxides and/or metal nitrides, optionally combined with an inorganic layer, achieving a thickness of up to 50 μm and a height of 150 μm or less, ensuring high precision, stability, and mechanical flexibility, with a CTE that matches or is closer to the sensor metal, allowing for quick environmental response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic substrate is used for thin-film temperature sensors, then the coefficient of thermal expansion matches the sensor metal, but the mechanical stability deteriorates when the substrate thickness is below 500 μm
Solution Approach 1:
The patent changes the thickness parameter of the ceramic substrate from conventional thick substrates (>500 μm) to thin substrates (50-1000 μm), and combines it with a polymer support structure. This parameter change enables the substrate to be thin enough for flexibility while the polymer provides the necessary mechanical stability during handling and processing.
Solution Approach 2:
The patent creates a composite structure by combining the ceramic substrate (providing thermal expansion match and sensing functionality) with a polymer support structure (providing mechanical stability). This composite approach allows each material to contribute its advantageous properties while compensating for the weaknesses of the other.
2Adaptability or versatility
If the substrate thickness is reduced below 500 μm, then the flexibility improves, but the mechanical stability and handleability deteriorate
Solution Approach 1:
The patent uses a composite structure where the thin ceramic substrate (50-1000 μm) provides flexibility and thermal matching, while the polymer support structure provides mechanical stability during handling. The polymer acts as a temporary support that can be removed after the thin-film sensor is fabricated and mounted.
Solution Approach 2:
The patent optimizes the substrate thickness parameter to the range of 50-1000 μm, which is thin enough to provide flexibility and fast thermal response, but not so thin that it becomes unhandleable without support. The polymer support enables handling even at the lower end of this range.
3Adaptability or versatility
If a polymeric substrate is used, then the flexibility and thinness are improved, but the coefficient of thermal expansion becomes too high and shape stability deteriorates
Solution Approach 1:
The patent uses a composite where the polymer substrate provides flexibility and ease of processing, while the thin ceramic layer (50-1000 μm) provides the necessary thermal expansion match with the metal film. The ceramic layer acts as the functional sensing element with proper thermal properties, while the polymer serves as a support structure.
Solution Approach 2:
The patent applies different materials with different properties to different layers of the structure. The polymer substrate provides mechanical flexibility and ease of handling, while the thin ceramic layer provides thermal expansion matching and sensing functionality. Each layer performs its specific function locally.
4Speed
If the substrate thickness is reduced to increase flexibility, then the response time to environmental changes improves, but the mechanical stability during processing deteriorates
Solution Approach 1:
The patent combines a thin substrate (for fast response) with a polymer support structure (for easy handling during processing). The polymer support allows the thin substrate to be manipulated, patterned, and processed without breaking, while the thin substrate ensures rapid thermal response once the sensor is assembled.
Solution Approach 2:
The polymer support structure acts as a protective cushion during the fabrication and handling process. It prevents the thin substrate from breaking during processing steps, and can be removed after the sensor is completed and mounted, leaving the thin substrate intact for fast response operation.
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 precise, flexible, and stable sensor with rapid responsiveness and low mass, maintaining mechanical stability and accuracy even under bending stress, with minimal resistance change, suitable for various environmental measurements.
Implementation Method 1
the electrical resistance of the metal sheet R(T) changes according to R(T) = R(0)·(1 + ξ(T)·ΔT), with R(0) equal to the resistance at T=0
Implementation Method 2
Ideally, the substrate should have a similar coefficient of thermal expansion (CTE) to that of the sensor metal deposited on it. Especially, if the CTE of the substrate is larger than that of the metal, cracks in the metal layer can occur
Data Source
Figure 1~2
Figure 3A~3D
Figure 3E~3H
AI summary
A flexible passive electronic component comprises a substrate, which comprises an insulating layer and optionally an inorganic layer with an upper side and a lower side, whereby the insulating layer at least partially covers the upper side of the optional inorganic layer. The flexible passive electronic component further comprises an electrical structure at least partially covering the insulating layer. The substrate has a thickness, which is at most 50 µm. The flexible passive electronic component has a height, which is at most 150 µm.