Integrated Diaphragm Pressure Sensor Chip Attachment
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Solution Overview
Problem
Pressure sensors with metal diaphragms face issues due to material compatibility and thermal expansion differences between semiconductor chips and stems, leading to potential detachment, increased part count, complexity, and leakage risks.
Innovation Solution
A pressure sensor design where the semiconductor chip is mounted on a diaphragm integrated with the housing, with specific area and thickness settings to prevent separation, allowing the same material to be used for both, eliminating the need for a matching thermal expansion coefficient and reducing the number of parts and structural complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stem is made of kovar to match the thermal expansion coefficient of the semiconductor chip, then the semiconductor chip remains attached to the stem, but the housing cannot be made of stainless steel or aluminum due to corrosion resistance and cost considerations
Solution Approach 1:
The patent divides the housing into two functional parts: a stem portion that contacts the semiconductor chip and a housing portion that provides structural support and fluid containment. The stem portion is made of kovar to match the thermal expansion coefficient of the semiconductor chip, while the housing portion can be made of stainless steel or aluminum for corrosion resistance and cost effectiveness. This segmentation allows different materials to be used in different parts of the housing based on their specific functional requirements.
2Ease of manufacture
If the housing and stem are made of different materials, then material optimization is achieved, but the number of parts increases and the structure becomes complicated
Solution Approach 1:
The patent merges the housing and stem into a single integrated component. The housing is designed with a stem portion that is integral to the housing body, eliminating the need for separate stem and housing parts. This integration simplifies the overall structure, reduces the number of parts, and eliminates the need for sealing between the stem and housing, while still allowing different materials to be used in different portions of the integrated structure.
3Ease of manufacture
If the housing and stem are made of different materials, then material optimization is achieved, but sealing requirements increase to prevent fluid leakage
Solution Approach 1:
The patent merges the housing and stem into a single integrated component, eliminating the seam between them. This integration completely eliminates the sealing requirement at the interface between housing and stem, as there is no seam where fluid could leak. The integrated structure provides inherent sealing by design, removing this potential failure point entirely.
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
This design prevents separation between the semiconductor chip and diaphragm, simplifies the sensor structure, and ensures proper sealing, reducing fluid leakage and enhancing operational reliability.
Implementation Method 1
The semiconductor chip includes a strain gauge for producing an electrical signal corresponding to deformation of the diaphragm caused by pressure of the fluid
Implementation Method 2
The housing has a thin-wall portion at the first end of the inlet and the thin-wall portion serves as the diaphragm
Data Source
AI summary
A pressure sensor includes a metal housing and a semiconductor chip. The housing has a diaphragm unitary with the housing and an inlet for introducing fluid to the diaphragm. The inlet has a first end exposed to the diaphragm and a second end exposed to an outside of the housing. The housing has a thin-wall portion at the first end of the inlet and the thin-wall portion serves as the diaphragm. The chip is mounted on the diaphragm. The area and thickness of the chip are set so that separation between the chip and diaphragm can be prevented. Since the separation is prevented based on the area and thickness of the chip, there is no need that the diaphragm is made of a material having a thermal expansion coefficient similar to that of the chip.