Hermetic Gas Flow Sensor Packaging for Corrosive Vacuum Environments
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensors used in manufacturing systems are not compatible with aggressive environments, such as corrosive conditions, high energy plasma, vacuum, and high temperatures, and fail to maintain vacuum seals while accurately measuring and controlling gas flow rates.
Innovation Solution
A sensor assembly comprising a substrate with defined regions and electrical contact pads, a housing for hermetic sealing, and a sensor die aligned via alignment features, bonded with metal bonds like platinum or multilayer reactive foils, to withstand aggressive environments and maintain accurate gas flow measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sensors are used in aggressive manufacturing environments, then they can be easily manufactured and installed, but they fail to maintain vacuum seals and are corrupted by corrosive conditions, plasma, and high temperatures
Solution Approach 1:
The sensor packaging is divided into distinct functional regions: a first region hermetically sealed to protect the sensor die from aggressive environments, and a second region exposed to process gases for measurement. This segmentation allows the sensor to simultaneously maintain vacuum integrity and interact with process gases, resolving the contradiction between reliability in aggressive environments and ease of manufacture.
Solution Approach 2:
Different regions of the packaging are given different properties: the first region has hermetic sealing properties to protect against corrosion and maintain vacuum, while the second region has open flow properties to allow gas measurement. This local differentiation of properties enables the sensor to function reliably in aggressive environments without excessive manufacturing complexity.
2Measurement precision
If the sensor packaging is designed with special geometry to minimize adverse effects on gas flow properties, then measurement accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The packaging is segmented into a first hermetically sealed region and a second region exposed to process gases. This segmentation creates distinct functional zones that simplify the overall geometry while maintaining measurement accuracy - the second region can be optimized for gas flow characteristics without complicating the entire packaging structure.
Solution Approach 2:
The patent introduces a spatial dimension by creating separate regions at different locations on the substrate. The first region is positioned for hermetic sealing while the second region is positioned for gas flow exposure, allowing independent optimization of each region's geometry for its specific function without increasing overall device complexity.
3Measurement precision
If the sensor die is directly exposed to process gases for accurate measurement, then measurement sensitivity improves, but the sensor becomes vulnerable to corrosion and material contamination
Solution Approach 1:
The substrate is divided into a first region for hermetic sealing and a second region exposed to process gases. The sensor die can be positioned in or near the second region to maintain measurement sensitivity while the first region provides hermetic protection, resolving the contradiction between exposure for measurement and protection from harm.
Solution Approach 2:
The substrate itself acts as an intermediary structure that enables the sensor die to access process gases for measurement while simultaneously providing a hermetically sealed pathway for electrical connections and signal transmission. This intermediary structure allows the sensor to function without direct vulnerability to corrosive environments.
4Reliability
If a hermetic seal is implemented to protect the sensor from aggressive environments, then reliability improves, but gas flow measurement capability deteriorates
Solution Approach 1:
The packaging is segmented into a first hermetically sealed region and a second region open to process gases. This segmentation allows the sensor to simultaneously maintain vacuum integrity through the first region while preserving gas flow measurement capability through the second region, eliminating the trade-off between hermetic protection and measurement functionality.
Data Source
AI summary
Certain embodiments of the present disclosure relate to a sensor assembly including a housing having a first channel configured to flow a gas in a first direction and a second channel configured to flow the gas in a second direction. The housing is configured to couple to a gas flow assembly. A substrate is disposed within the housing. The substrate has an outer region, an inner region within the first channel, and a middle region between the outer region and the inner region. The substrate further includes electrical contact pads on at least the inner region. A sensor die is coupled to the inner region of the substrate, having an electrical connection to the electrical contact pads. The sensor die is disposed within a gas flow path of the first channel.