Integrated Sensor Assembly Diaphragm Fatigue Prevention
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Solution Overview
Problem
Conventional force sensors face issues with package tolerance control, size reduction limitations, sensor diaphragm contact fatigue, exposure of electrical sensing elements to the environment, and potential diaphragm damage from overload forces due to separate construction and assembly of sensor die and actuation elements.
Innovation Solution
The sensor assembly integrates a sensor die with a diaphragm and actuation element formed from silicon, where the actuation element is integral with the first member and positioned directly on the diaphragm, and a recessed section in the second member limits diaphragm deflection, with electrical sensing elements and metallic contacts for surface mount connections, protecting the components from environmental exposure and reducing fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate construction and assembly of sensor die and actuation element are used, then ease of manufacture is improved, but manufacturing precision deteriorates due to package tolerance control requirements
Solution Approach 1:
The actuation element and sensor die are merged into a single integrated structure where the actuation element is formed as an integral part of the sensor die. This eliminates the separate assembly step and associated package tolerance control requirements, thereby improving manufacturing precision while maintaining ease of manufacture through monolithic fabrication.
2Ease of manufacture
If separate construction and assembly of sensor die and actuation element are used, then ease of manufacture is improved, but device size reduction is limited
Solution Approach 1:
By integrating the actuation element directly into the sensor die as a monolithic structure, the overall device volume is reduced compared to separate assembly. The merged design eliminates gaps and interface layers between separate components, enabling further size reduction while maintaining manufacturing simplicity through single-step fabrication processes.
3Ease of operation
If repeated contact between actuation element and sensor die diaphragm occurs, then force sensing function is maintained, but sensor diaphragm contact fatigue issues arise shortening service life
Solution Approach 1:
The actuation element and diaphragm are merged into a single integral structure, eliminating repeated contact and relative motion between separate components. This prevents contact fatigue while maintaining the force sensing function through the integrated structure's inherent mechanical coupling, thereby extending service life.
Solution Approach 2:
The sensor die is segmented into distinct functional regions including the actuation element and diaphragm areas, with the recessed section providing structural separation that prevents direct contact fatigue while maintaining force transmission capability for sensing operations.
4Ease of manufacture
If electrical sensing elements are exposed to external environment, then ease of manufacture is improved, but performance is influenced by environmental factors
Solution Approach 1:
The electrical sensing elements are nested within the sensor die structure, specifically positioned in the recessed section that provides environmental protection. This nested arrangement shields the sensitive electrical components from external environmental factors while maintaining ease of manufacture through integrated fabrication processes.
Solution Approach 2:
The sensor die structure itself acts as a protective shell enclosing the electrical sensing elements, providing environmental isolation while allowing the thin-film diaphragm to remain exposed for force sensing functionality. This protective enclosure prevents environmental degradation of the electrical components.
5Ease of manufacture
If no feature limiting diaphragm deflection is included, then ease of manufacture is improved, but diaphragm damage from overload external force occurs
Solution Approach 1:
The recessed section is pre-formed in the sensor die structure to establish a mechanical limit on diaphragm deflection before overload conditions occur. This preliminary structural feature prevents excessive deflection and potential diaphragm damage from overload forces while maintaining ease of manufacture through integrated fabrication of the recessed section with the sensor die.
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 integrated construction enhances manufacturing precision, reduces diaphragm damage, and extends the service life of force sensors by controlling deflection and protecting electrical components, while maintaining sensitivity and force detection capabilities.
Implementation Method 1
The diaphragm includes an actuating member extending away from the diaphragm. The diaphragm support includes a recess located opposite the portion of the diaphragm including the actuating member... causing the diaphragm to deflect, which deflection is measured by the electrical sensing elements
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
A sensor assembly (40) comprising a sensor die (42) including a first member (44) and a second member (46). The first member (44) comprises a diaphragm (54) extending between first and second opposed surfaces (50, 48) of the first member (44). A number of electrical sensing elements (58) are disposed within the first member (44) and positioned adjacent the diaphragm (54) along the first surface (50). The second member (46) is attached with the first member (44) along the first surface (50) comprising the electrical sensing elements (58). The second member (46) has a recessed section (75) forming cavity (76) with the first member (44) to accommodate deflection of the diaphragm (54). The first member (44) includes an actuation element (47) that extends outwardly from the second surface (48) and that is positioned directly on the diaphragm (54). The sensor assembly (40) includes metallic connectors (56) and contacts (60) for facilitating connection between the electrical sensing elements (58) and an outer surface (66) of the sensor die to provide a surface mount electrical connection of the sensor assembly (40).