Wafer-Level Retention for Compact Force Sensor Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a challenge in developing small force sensors that can be easily and cost-effectively integrated into consumer electronics, requiring sensors that are compact enough to fit within limited footprints while maintaining effective force measurement capabilities.
Innovation Solution
A low-cost small force sensor design featuring a sense die assembly with a cavity and diaphragm, an actuation element, and a cover member that provides wafer-level retention, allowing for miniaturization to a footprint area of less than 25 mm², utilizing etched silicon wafers and piezoresistive sensing elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional force sensor designs are used, then force measurement capability is achieved, but the sensor size and complexity increase, making integration into consumer electronics difficult
Solution Approach 1:
The patent combines multiple components (sense die with cavity, diaphragm, actuation element, and cover member) into a single integrated sense die assembly. The cover member is formed directly on the sense die, and the actuation element is retained within the cavity, eliminating the need for separate housings and simplifying the overall structure while maintaining force measurement capability.
Solution Approach 2:
The actuation element is nested within the cavity of the sense die, which is formed by etching. The cover member is formed on the sense die and encloses the cavity, creating a nested structure where the actuation element is contained within the sense die assembly. This nesting approach minimizes the overall footprint while retaining all necessary functional components.
2Area of moving object
If sensor size is reduced to fit consumer electronics footprints, then integration ease improves, but manufacturing precision and reliability become more challenging
Solution Approach 1:
The cover member is formed directly on the sense die through a bonding or growth process, creating a self-contained structure. The etched cavity and cover member geometry are designed to provide automatic mechanical retention of the actuation element without requiring additional retention structures or complex assembly steps, thereby simplifying manufacturing while maintaining precision.
3Area of moving object
If miniaturization is achieved with footprint less than 25 mm², then space efficiency improves, but cost-effectiveness and reliable performance may be compromised
Solution Approach 1:
The patent replaces complex mechanical retention mechanisms with a wafer-level integration approach. The cover member is formed on the sense die using bonding or growth processes, and the etched cavity geometry provides automatic mechanical retention of the actuation element. This substitution of complex mechanical systems with integrated wafer-level structures reduces manufacturing steps and costs while maintaining miniaturization benefits.
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 solution enables the creation of highly compact force sensors that can accurately measure forces within small footprints, suitable for applications requiring minimal space, while maintaining cost-effectiveness and reliable performance.
Implementation Method 1
one or more sensing elements positioned on a bottom side of the diaphragm
Data Source
Figure 1~2
AI summary
Disclosed herein are force sensors which include a sense die assembly and methods for manufacturing the sense die assembly and the force sensor. The disclosed sense die assembly, force sensor, and methods utilize wafer-level retention to hold an actuation element in a cavity of the sense die.