Pressure Sensor Gel Coating With Polymer Diffusion Barrier
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Solution Overview
Problem
Pressure sensors in harsh and corrosive environments face issues with chemical corrosion and diffusion through existing gel coatings, leading to damage of sensitive components.
Innovation Solution
A thin, cross-linked polymer adhesive layer is applied on top of the gel coating to form a barrier, reducing chemical diffusion and protecting sensitive elements while maintaining pressure sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gel coating is applied to protect the sensing die, then chemical corrosion is reduced, but chemical diffusion through the gel still occurs over time
Solution Approach 1:
The patent applies a dual-layer protective system combining a gel coating layer with a polymer adhesive layer. The gel coating provides initial chemical protection while the polymer adhesive layer acts as a diffusion barrier. This composite structure leverages the complementary properties of both materials to achieve superior long-term chemical resistance compared to either material alone.
Solution Approach 2:
The polymer adhesive layer functions as a thin film barrier that is flexible enough to accommodate the sensing die while providing effective chemical diffusion protection. The thin film structure maintains pressure sensitivity by allowing mechanical deformation while blocking chemical species.
2Reliability
If the gel coating thickness is increased to improve chemical protection, then diffusion barrier is enhanced, but device compactness is compromised
Solution Approach 1:
Instead of increasing gel thickness, the patent uses a composite approach with a thin polymer adhesive layer providing the primary diffusion barrier function. This allows achieving effective chemical protection with minimal additional volume, maintaining device compactness while improving reliability.
Solution Approach 2:
The patent changes the material parameter from gel-only protection to a polymer-adhesive-based diffusion barrier. This material substitution enables effective chemical protection with a much thinner layer, preserving the compact form factor of the pressure sensor device.
3Reliability
If a protective layer is added to prevent chemical diffusion, then reliability is improved, but sensitivity of the pressure sensor may be reduced
Solution Approach 1:
The polymer adhesive layer is designed as a thin film that is mechanically flexible, allowing it to deform with the sensing die under pressure. This flexibility ensures that the protective layer does not significantly attenuate the pressure signal, maintaining sensor sensitivity while providing chemical diffusion protection.
Solution Approach 2:
The patent optimizes the thickness and material properties of the polymer adhesive layer to balance chemical barrier performance with mechanical transparency to pressure. By carefully controlling these parameters, the layer provides effective diffusion protection while minimizing impact on pressure transmission and sensor sensitivity.
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 additional polymer layer effectively prevents chemical corrosion and diffusion, maintaining sensor sensitivity and compactness without significant mechanical stress.
Implementation Method 1
The additional layer acts as a barrier to pollutants and chemicals from the environment. It reduces or prevents diffusion of chemicals
Implementation Method 2
The coating allows the transmission of the pressure to be measured from the environment
Implementation Method 3
stress gradients and/or differences due to different expansion, caused by temperature or chemical swelling
Implementation Method 4
stress gradients and/or differences due to different expansion, caused by temperature or chemical swelling
Data Source
Figure 1~2
Figure 3~4
AI summary
A pressure sensor comprises a package with a cavity and a sensing die. The sensing die is placed within the cavity. The sensor comprises a gel coating provided inside the cavity covering at least the sensing die. The gel coating has a pressure-receiving surface. The sensor further comprises a layer of a polymer in contact with the pressure-receiving surface of the gel coating. The polymer is an adhesive, the polymer being different from the material of the gel coating.