Waterproof Pressure Sensor Assembly with Stress-Absorbing Spacer
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Solution Overview
Problem
Existing microphones and pressure sensors face challenges in high-humidity and water-submersible environments due to corrosion, limited diaphragm size, and thermal expansion mismatches, leading to reliability issues and performance degradation.
Innovation Solution
A pressure sensor device with a non-corrosive housing, silicon sensor chip, thermally matched spacer, and electrical feedthrough pins, sealed to protect internal components and minimize thermal stress, allowing for large diaphragm operation in harsh environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If regular audio microphone components are used in water or high humidity environments, then the device can be manufactured with standard materials and processes, but the components will corrode and damage when exposed to water
Solution Approach 1:
The device is divided into separate functional components: a corrosion-resistant housing that protects internal electronics, a diaphragm that interfaces with the acoustic environment, and sealed compartments that isolate sensitive components from moisture. This segmentation allows each component to be optimized for its specific function while protecting against corrosion.
Solution Approach 2:
A corrosion-resistant housing and sealing structures act as intermediaries between the external corrosive environment and the internal electronic components. These protective barriers prevent direct contact between water/moisture and sensitive electronics, allowing standard components to be used internally while achieving overall corrosion resistance.
2Measurement precision
If the diaphragm is made relatively large to improve sensitivity at low frequencies, then low-frequency pressure detection capability is improved, but the device complexity and sealing requirements increase to avoid corrosion
Solution Approach 1:
The large diaphragm is implemented as a separate component that can be independently sealed and mounted. The diaphragm assembly is isolated from internal electronics through sealed compartments, allowing the diaphragm size to be optimized for low-frequency sensitivity without increasing the complexity of protecting internal components.
Solution Approach 2:
The diaphragm is extracted as a distinct functional element that interfaces with the acoustic environment, while the electronics and sensitive components are housed in a separate protected compartment. This separation allows the diaphragm to be large and exposed to the environment without compromising the protection of internal components.
3Ease of operation
If rigid wire connections are used for electrical interconnections, then electrical connectivity is established, but the connections can fail or impart stress on the diaphragm in large diaphragm applications
Solution Approach 1:
Rigid wire connections are replaced with flexible wiring solutions such as wire bonds or flexible traces that can accommodate the mechanical movements of the diaphragm without failing. This dynamic connection approach maintains electrical connectivity while preventing stress transmission to the diaphragm during operation.
4Ease of manufacture
If standard packaging materials are used for sensor housing, then manufacturing is simplified, but thermal expansion mismatches occur within the device
Solution Approach 1:
The housing and internal components are selected and designed with compatible coefficients of thermal expansion. By carefully choosing materials whose thermal expansion characteristics match, the device maintains structural stability across temperature variations without requiring complex compensation mechanisms.
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
Enhances reliability and performance by protecting internal components from corrosion and thermal stress, enabling large diaphragm operation for sensitive pressure measurements in high-humidity and underwater applications.
Implementation Method 1
A back end of the pressure sensor device is hermetically sealed so that only a backside of the sensor chip, the spacer layer, and the housing is exposed to pressure media during use
Implementation Method 2
an electrically insulating and stress-absorbing spacer layer disposed between the non-corrosive housing and the contact glass of the sensor chip
Data Source
AI summary
A pressure transducer assembly configured for low-pressure measurements in water or high humidity environments, the pressure transducer assembly having a non-corrosive housing, an upside-down mounted pressure sensor chip comprising silicon and contact glass, and an electrically insulating and stress-absorbing spacer layer disposed between the non-corrosive housing and the contact glass of the sensor chip, the spacer layer is matched to a coefficient of thermal expansion (CTE) of one or more of the glass and the silicon of the sensor chip to absorb stress and improve reliability. The pressure transducer assembly may be suitable for use in microphone and/or hydrophone applications.