Pressure Sensor Element With Partition Wall Isolating External Stress
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Solution Overview
Problem
Miniaturization of electronic components has led to precision issues in pressure sensors due to external stress being transferred to the membrane, affecting sensing characteristics and reducing sensor precision.
Innovation Solution
A pressure sensor element with a die featuring a concave groove, partition wall, and membrane is designed, where the partition wall and trench form separate spaces to isolate external forces, preventing deformation of the sensing membrane and using a flexible membrane with piezoresistors to measure pressure, and an adhesive layer to isolate substrate deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional pressure sensor structure is used, then the sensor can detect pressure, but external stress from the package is transferred to the membrane through the die, decreasing measurement precision
Solution Approach 1:
The die is segmented into distinct functional regions: a sensing region where the membrane is located and an outer region that absorbs stress. The concave groove partitions the die into these regions, isolating the sensing membrane from external stress generated at the package periphery. This segmentation prevents stress transfer while maintaining pressure sensing capability.
Solution Approach 2:
The concave groove structure acts as an intermediary stress-absorbing layer between the package exterior and the sensing membrane. The groove walls and bottom provide a mechanical buffer that absorbs external stresses before they can reach the membrane, protecting the sensing element from deformation.
2Area of stationary object
If the membrane covers the entire die surface, then it provides complete coverage, but it deforms when external forces are applied to the outer portion of the die
Solution Approach 1:
The membrane coverage is segmented into a central sensing area and peripheral areas. The concave groove creates a physical boundary that restricts membrane deformation to the sensing region while isolating the peripheral membrane portions from stress-induced deformation. This allows extensive coverage while maintaining sensing reliability.
Solution Approach 2:
Different regions of the membrane have different functional qualities: the central region over the cavity provides stress-sensitive detection, while peripheral regions over the groove walls provide structural support and stress isolation. This local differentiation allows the membrane to simultaneously achieve extensive coverage and deformation resistance.
3Volume of moving object
If miniaturization is pursued to reduce sensor size, then electronic products become more compact, but precision decreases due to increased sensitivity to external stress
Solution Approach 1:
The sensing membrane is nested within the concave groove structure, which itself is nested within the die. This nested configuration allows the sensor to maintain a compact overall size while the groove provides an internal stress-absorbing structure that protects the membrane from external stresses, preserving precision in miniaturized form.
Solution Approach 2:
The concave groove introduces a vertical dimension to the stress management strategy. By creating depth in the die structure, the groove provides stress absorption pathways in the vertical direction, allowing the sensor to maintain precision without increasing lateral dimensions, thus enabling miniaturization without precision loss.
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 effectively blocks external forces from affecting the sensing membrane, maintaining measurement reliability and precision by isolating deformations and allowing for precise pressure measurement.
Implementation Method 1
a piezoresistive type pressure sensor which can sense stress generated when a membrane covering a cavity of a die is deformed by pressure
Data Source
AI summary
A pressure sensor element includes a die; a cavity and a trench formed in one surface of the die and defining therebetween a partition wall integral with and formed of the same material as the die; and a membrane formed on the die and covering the cavity and the trench.