Flexible Passive Component Substrate for Stable Thin-Film Sensing
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Solution Overview
Problem
Current thin-film temperature sensors face challenges with mechanical stability and precision due to the limitations of ceramic and polymeric substrates, particularly when thickness is below 500 µm, leading to potential cracking and temporal changes in polymeric substrates, which affect the accuracy and reliability of temperature measurements.
Innovation Solution
A flexible passive electronic component with a substrate formed from an insulating layer and an inorganic layer, with a total thickness of at most 50 µm and height of at most 150 µm, utilizing an inorganic layer with low coefficient of thermal expansion to ensure stability and flexibility, allowing for quick response to environmental changes without temporal changes or mechanical instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic substrate is used to ensure mechanical stability, then reliability is improved, but the substrate thickness must be at least 500 µm which increases device height and reduces flexibility
Solution Approach 1:
The patent uses a composite substrate structure combining a polymer base layer with a ceramic layer (aluminum oxide, aluminum nitride, or silicon oxide) deposited on top. This composite approach allows the thin polymer layer to provide flexibility while the thin ceramic layer (5-50 µm) provides mechanical stability and appropriate CTE matching, resolving the contradiction between reliability and thickness.
Solution Approach 2:
The patent employs thin film technology to deposit ceramic layers (5-50 µm) and metal sensor layers (0.1-10 µm) onto a flexible polymer substrate. This thin-film approach enables the substrate to maintain mechanical stability through the ceramic layer while achieving overall thickness below 50 µm, providing both reliability and flexibility.
2Ease of operation
If a polymeric substrate is used to achieve flexibility, then ease of operation is improved, but the substrate changes shape or physical properties over time which worsens measurement precision
Solution Approach 1:
The patent combines a polymer substrate with a ceramic layer having appropriate CTE (6.5-8.9E-6 1/K for aluminum oxide). The ceramic layer acts as a stabilizing element that compensates for the polymer's temporal changes, maintaining dimensional stability and measurement precision while the polymer provides flexibility.
Solution Approach 2:
The patent carefully selects and controls the thickness parameters of both polymer and ceramic layers, as well as their material properties (CTE matching). By optimizing these parameters, the substrate maintains flexibility while the ceramic layer's stable thermal expansion characteristics compensate for polymer creep and relaxation over time.
3Ease of operation
If the substrate is thinned below 500 µm to improve flexibility, then ease of operation is improved, but mechanical stability deteriorates and cracks can occur in the metal layer
Solution Approach 1:
The patent uses a composite structure with a polymer base layer and a thin ceramic layer (5-50 µm) deposited on top. The ceramic layer provides mechanical reinforcement and stress distribution, preventing cracks in the metal sensor layer even when the total substrate thickness is reduced below 50 µm, while maintaining flexibility.
Solution Approach 2:
The patent applies the ceramic layer selectively on the substrate where mechanical reinforcement is needed, particularly in regions with metal sensor deposits. This localized reinforcement provides strength where required while maintaining overall flexibility of the thin substrate structure.
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, suitable for various applications including temperature, flow, and chemical sensing.
Implementation Method 1
The CTE of Al 2 O 3 is 6.5-8.9E-6 (1/K) and is therefore similar to the CTE of the platinum with 8.8E-6 (1/K)... the inorganic layer shows no temporal change and has a relatively low CTE
Implementation Method 2
the electrical resistance of the metal sheet R(T) changes according to R(T) = R(0)·(1 + ξ(T)·ΔT)... the electric resistance of the electrical structure changes by the external input
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.