Hermetic Vacuum Pressure Sensor Structure for Low-Degassing Accuracy
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Solution Overview
Problem
Vacuum pressure sensors face challenges in withstanding high-vacuum environments due to degassing and material compatibility issues, particularly in semiconductor manufacturing, leading to sensor deterioration and inaccurate readings.
Innovation Solution
A vacuum pressure sensor design featuring a weld ring, header element, and piezoresistive sensing element with hermetic seals, a corrugated diaphragm, and a plastic spacer, using laser or resistance welding to prevent degassing and optimize silicone oil volume for improved accuracy and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional vacuum pressure sensors are used in high-vacuum environments, then they can measure pressure, but they suffer from degassing and material compatibility issues leading to sensor deterioration
Solution Approach 1:
The patent changes the material parameters by using platinum iridium alloy (80/20 PtIr) for the diaphragm and seal elements, which have superior material compatibility and zero degassing properties in high-vacuum environments compared to traditional materials. This material parameter change resolves the degassing issue while maintaining pressure measurement functionality.
Solution Approach 2:
The patent employs composite material structures including platinum iridium alloy combinations and hermetic sealing configurations that prevent material interaction and degassing. The composite approach uses multiple materials with complementary properties to achieve both vacuum compatibility and structural integrity.
2Ease of manufacture
If the cavity volume is increased to accommodate sensing elements, then easier assembly is achieved, but thermal errors increase due to larger oil volume
Solution Approach 1:
The patent applies local quality by providing hermetic sealing only at specific critical locations (header pins to header element, diaphragm edges) rather than sealing the entire cavity. This localized sealing approach maintains vacuum integrity while minimizing the volume of thermal-conductive oil, thereby reducing thermal errors without compromising assembly ease.
Solution Approach 2:
The patent extracts and removes excess oil from the cavity by using a controlled volume filling process and gravitational drainage during assembly. The cavity is filled with oil only to the extent necessary for thermal compensation, and excess oil is removed, thereby minimizing thermal errors while maintaining sufficient oil for sensor operation.
3Reliability
If hermetic sealing is implemented to prevent degassing, then vacuum integrity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements self-service hermetic sealing where the platinum iridium alloy diaphragm and seal elements inherently provide vacuum integrity through their material properties and geometric configuration, without requiring additional complex sealing mechanisms. The hermetic seals are integrated into the structural design itself, eliminating the need for separate sealing components.
4Stability of the object's composition
If silicone oil volume is increased for thermal compensation, then thermal stability improves, but degassing and vacuum contamination increase
Solution Approach 1:
The patent changes the physical parameters of the sealing system by using a corrugated diaphragm structure with reduced free volume and platinum iridium alloy materials with zero vapor pressure. This allows achieving thermal stability with minimal oil volume, as the thermal compensation is provided by the mechanical compliance of the diaphragm rather than bulk oil thermal expansion.
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 design prevents degassing events, reduces thermal errors, and enhances sensor performance by minimizing oil volume, ensuring accurate pressure measurements in high-vacuum conditions.
Implementation Method 1
a piezoresistive sensing element coupled to the header element
Implementation Method 2
a corrugated diaphragm coupled to the header element and the weld ring, wherein the diaphragm, along with the header element, defines a cavity
Implementation Method 3
one or more header pins hermetically sealed to the header element
Implementation Method 4
a plastic spacer disposed within the cavity, wherein the plastic spacer is coupled to the header element
Data Source
AI summary
A vacuum pressure sensor may comprise a weld ring and a header element welded to the weld ring. The header element may comprise one or more header pins hermetically sealed to the header element, a piezoresistive sensing element coupled to the header element and electrically coupled to the one or more header pins, a corrugated diaphragm coupled to the header element and the weld ring, wherein the diaphragm, along with the header element, defines a cavity that is configured to contain a material, and a plastic spacer disposed within the cavity. The vacuum pressure sensor may comprise a protruding, pointed edge or a substantially flat edge with no corner break of at least a portion of the header element in physical contact with the metal plate.