Sense Die Structural Frame for Overforce Protection
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Solution Overview
Problem
Force sensors often experience damage due to overforce conditions beyond their designed operating ranges, and existing protection mechanisms like mechanical diaphragm stops and attachment methods can deform under installation forces, leading to inconsistent performance.
Innovation Solution
A sense die design featuring a structural frame around the diaphragm with controlled offset height, which acts as a mechanical stop and supports the diaphragm, eliminating the need for deformable attachment methods like solder balls, and includes electrical contacts formed through the frame for secure connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical diaphragm stops or deformable attachment methods (e.g., solder balls) are used for overforce protection, then the sensor can withstand installation forces, but the attachment methods deform under installation forces leading to inconsistent performance
Solution Approach 1:
The sensor structure is segmented into distinct functional zones: a rigid structural frame providing mechanical support and overforce protection, and a separate sensing area with the diaphragm and piezoresistive elements. This segmentation allows the frame to handle installation forces while the sensing elements maintain consistent performance, resolving the contradiction between overforce protection and performance consistency.
Solution Approach 2:
Different regions of the sensor have different mechanical properties: the structural frame is designed with high rigidity to withstand installation forces, while the diaphragm area maintains controlled flexibility for accurate force sensing. This local differentiation of mechanical properties allows the sensor to simultaneously achieve overforce protection and consistent sensing performance.
2Reliability
If a structural frame with controlled offset height is used to protect the diaphragm, then overforce damage is prevented, but the device complexity increases
Solution Approach 1:
The structural frame serves multiple functions simultaneously: it provides mechanical support for the sensing elements, defines the sensing area, protects the diaphragm from overforce damage, and establishes the offset height for consistent performance. By merging these functions into a single integrated structure, the design achieves diaphragm protection without proportionally increasing device complexity.
Solution Approach 2:
The structural frame is designed as a multi-functional component that performs mechanical support, protective stopping, geometric definition, and structural stabilization. This multi-functionality reduces the need for separate protective components, thereby limiting the increase in device complexity while achieving reliable diaphragm protection.
3Reliability
If the structural frame height is increased to prevent overforce damage, then the diaphragm is better protected, but the measurement precision may be affected
Solution Approach 1:
The offset height of the structural frame is precisely controlled within a specific range (0.5-5 micrometers) to optimize both protection and measurement performance. This parameter optimization ensures the frame provides sufficient overforce protection while maintaining the diaphragm's sensitivity to normal operating forces, preventing degradation of measurement precision.
Solution Approach 2:
The structural frame provides more protection than the minimum required for overforce resistance by establishing a controlled offset that prevents diaphragm contact during normal operation. This partial excess action ensures robust protection while the controlled geometry maintains measurement precision through consistent mechanical behavior.
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 structural frame effectively protects the diaphragm from overforce damage by maintaining a consistent offset height and preventing deformation, ensuring accurate force measurement and extending the sensor's operational range without deforming under installation forces.
Implementation Method 1
The sensing elements can include piezoresistive elements formed on the diaphragm
Data Source
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AI summary
A sense die (100) comprising: a chip comprising a sense diaphragm (102); one or more sense elements (120, 122, 124, 126) supported by the diaphragm (102); one or more bond pads (130, 132, 134, 136) supported by a first side (103) of the chip; a structural frame (104) disposed on the first side (103) of the chip; and one or more electrical contacts (106) extending through the structural frame (104), wherein the one or more electrical contacts (106) are electrically coupled to the one or more bond pads (130, 132, 134, 136).