Pressure Sensor Diaphragm Support for Sensitivity
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Solution Overview
Problem
Sanitary pressure sensors face limitations in sensitivity due to the need for high corrosion resistance and rigidity, which restricts the size of the semiconductor chip and reduces sensitivity, as increasing diaphragm thickness to enhance rigidity also decreases deformation and thus sensitivity.
Innovation Solution
A pressure sensor design featuring a rectangular semiconductor chip with at least three insulating support members fixed to the diaphragm at positions where maximum displacement occurs, allowing efficient transmission of diaphragm deformation to the chip, thereby increasing sensitivity while maintaining a small chip size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the film thickness of the diaphragm is increased to realize a structure in which the diaphragm does not easily break, then the reliability is improved, but the amount of deformation of the diaphragm is reduced and the sensitivity of the sensor is reduced
Solution Approach 1:
The patent applies local quality by providing support members at specific locations on the diaphragm rather than uniformly across the entire surface. The support members are strategically positioned to provide localized reinforcement where needed to prevent diaphragm breakage, while leaving other regions free to deform naturally, thus maintaining sensitivity. This selective support approach resolves the contradiction between overall rigidity and localized deformation capability.
Solution Approach 2:
The patent segments the diaphragm support structure by introducing discrete support members at specific positions rather than using a continuous support structure. This segmentation allows the diaphragm to maintain its overall structural integrity and rigidity while permitting localized deformation in regions without support members, thereby preserving sensor sensitivity despite increased overall thickness.
2Adaptability or versatility
If the diameter of the diaphragm is increased to accommodate a larger coupling, then the adaptability is improved, but the length of the semiconductor chip needs to be increased which reduces sensitivity
Solution Approach 1:
The patent resolves this contradiction by transitioning from a one-dimensional linear chip arrangement to a two-dimensional planar arrangement of support members and resistors. The support members are positioned at specific coordinates on the diaphragm surface, and the resistors are arranged in a Wheatstone bridge configuration on the chip surface. This dimensional change allows the system to accommodate larger diaphragm diameters while maintaining sensitivity through optimized spatial distribution rather than linear extension.
Solution Approach 2:
The patent extracts the support function from the entire diaphragm structure and concentrates it at specific discrete locations where support members are positioned. This extraction allows the majority of the diaphragm surface to remain free for deformation and sensing, while providing targeted reinforcement only where needed to prevent breakage, thus maintaining sensitivity despite larger overall dimensions.
3Stability of the object's composition
If both ends of the semiconductor chip are fixed to portions of the diaphragm that do not substantially move, then the stability is improved, but the sensitivity is reduced because large displacement of the central portion cannot be efficiently transmitted
Solution Approach 1:
The patent applies asymmetry by positioning support members at asymmetric locations on the diaphragm relative to the semiconductor chip. The support members are placed at specific points where the diaphragm displacement is maximized, creating an asymmetric support configuration that optimizes the transmission of displacement to the chip. This asymmetric arrangement allows the chip to experience enhanced displacement while maintaining stable mounting, resolving the contradiction between stability and sensitivity.
Solution Approach 2:
The patent introduces support members as intermediary elements between the diaphragm and the semiconductor chip. These support members act as mediators that transmit and amplify the displacement of the diaphragm central portion to the chip, while providing stable mounting points. The support members serve as mechanical levers that convert small diaphragm movements into larger, more detectable chip displacements, thus enhancing sensitivity while maintaining stability.
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 achieves high sensitivity with a small semiconductor chip by optimizing support member placement to maximize diaphragm displacement transmission, enhancing the pressure sensor's sensitivity and detectability without increasing chip size.
Implementation Method 1
when the diaphragm is bent, a large displacement of the central portion of the diaphragm can be efficiently transmitted to the semiconductor chip
Implementation Method 2
changes in the resistances of the diffused resistors due to the piezoresistive effect based on deformation of the semiconductor chip are detected
Data Source
AI summary
A pressure sensor according to the present invention includes a diaphragm (3) including a first principal surface (3A) and a second principal surface (3B) that is opposite thereto, the first principal surface receiving a pressure of a fluid; a semiconductor chip (1) provided with resistors that constitute a strain gauge; and at least three support members (2a, 2b, 2c) made of an insulating material, each support member being fixed to the second principal surface at one end thereof and to the semiconductor chip at the other end thereof and extending perpendicularly to the second principal surface so as to support the semiconductor chip. One of the support members (2a) is provided at a center (30) of the diaphragm in plan view. At least two of the other support members (2b, 2c) are provided at positions point-symmetrical about the center of the diaphragm in plan view in a region in which the diaphragm is deformed when a pressure greater than a pressure applied to the second principal surface is applied to the first principal surface.