Pressure Sensor Module Backside Barrier Design
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Solution Overview
Problem
Pressure sensor modules used in acidic environments, such as diesel exhaust, face degradation issues due to laser cutting processes creating micro cracks and vulnerable ceramic phases, leading to chemical attack and corrosion, which affects the protective gel's durability and the sensor's performance.
Innovation Solution
Incorporating a backside barrier with a protective gel in the pressure sensor module, which enlarges the distance between the gel surface and the hole walls, reducing water pocket formation and mechanical stress, and using a ceramic substrate with a sintering process to create a more robust surface texture, along with a front-side barrier and noble metal conductive elements for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser cutting is used to create through holes in ceramic support members, then manufacturing economy and ease of manufacture are improved, but the ceramic surface becomes vulnerable to chemical attack and corrosion due to micro cracks and glassy phase formation
Solution Approach 1:
A protective gel is introduced as an intermediary substance that fills the through hole and creates a barrier between the laser-cut ceramic surface and the acidic exhaust environment. The gel protects the vulnerable ceramic surface from chemical attack while allowing pressure transmission to the sensing element.
Solution Approach 2:
The patent changes the physical and chemical parameters of the ceramic surface through post-laser treatment processes such as annealing or chemical etching. This modifies the surface texture and removes vulnerable glassy phases, transforming the ceramic from a chemically vulnerable state to a more robust state resistant to acid corrosion.
2Reliability
If the through hole is filled with protective gel to isolate the sensing element from contaminants, then protection against chemical attack is improved, but water pockets and mechanical stress increase leading to gel degradation
Solution Approach 1:
The patent modifies the geometry of the through hole from a sharp cylindrical shape to a rounded or tapered configuration. This curvature eliminates sharp corners where water pockets would form and reduces stress concentration points, thereby preventing gel degradation and extending its service life in acidic environments.
Solution Approach 2:
The protective gel is pre-filled into the through hole before final assembly and sealing of the sensor housing. This preliminary action ensures that the gel is in place to protect the sensing element from chemical attack before the sensor is exposed to the acidic exhaust environment, establishing protection in advance.
3Ease of operation
If the sensing element is exposed to acidic medium through the through hole, then pressure measurement function is maintained, but the sensing element becomes prone to chemical attack and corrosion
Solution Approach 1:
The protective gel serves as an intermediary medium between the acidic exhaust environment and the sensing element. It allows pressure transmission (maintaining measurement function) while blocking direct contact between the sensing element and corrosive chemicals, thus protecting the sensing element.
Solution Approach 2:
The patent uses a flexible protective coating or membrane that covers the sensing element and lines the through hole. This thin flexible barrier protects the sensing element from chemical attack while allowing it to respond to pressure changes, maintaining the measurement function.
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 significantly extends the lifespan of the pressure sensor by slowing down gel degradation, maintaining accuracy and stability across a wide temperature range, and improving robustness against acidic conditions.
Implementation Method 1
a backside protective member filling the hole and at least partially the enclosed area
Implementation Method 2
using a ceramic substrate with a sintering process to create a more robust surface texture
Implementation Method 3
The enclosed area and the hole form a pressure channel
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A pressure sensor module is disclosed. The pressure sensor module comprises a sensing element 1 mounted on a front side 3 of a support member 5. The support member 5 comprises a hole 7 through the support member 5 from the front side 3 to a back side 9. The sensing element 1 covers the hole 7 at the front side 3. A backside barrier 6 provided at the backside 9 of the support member 5 surrounds a surface of the backside 9 of the support member 5 and forms an enclosed area 8, wherein the enclosed area 8 and the hole 7 form a pressure channel 10. A backside protective member 2 fills the hole 7 and at least partially the enclosed area 8. The support member 5, backside barrier 6 and backside protective member 2 form a module that can be placed during production of the pressure sensor in a housing of the pressure sensor.