Calibrating Pressure Sensor ICs Using Resonant Frequency
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Solution Overview
Problem
Capacitive pressure sensor IC devices require full recalibration over multiple calibration points after being attached to a circuit board, which is costly and impractical due to mechanical strain from solder balls and thermal expansion mismatch, leading to inaccurate data.
Innovation Solution
The method involves determining the resonant frequency of the membrane after attachment, calculating strain, and using a physical model to derive new calibration points for recalibration, employing the Thiele interpolation formula to generate a capacitance-to-pressure curve, reducing the need for multiple reference pressures and thus the cost and time of recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full recalibration over multiple calibration points is performed after attaching the pressure sensor IC device to a circuit board, then measurement precision is improved, but loss of time and manufacturing cost increase significantly
Solution Approach 1:
The patent extracts only the essential calibration information needed by measuring just one resonant frequency of the membrane, rather than performing full recalibration over multiple calibration points. This extraction approach obtains the necessary strain compensation data with minimal time investment, resolving the contradiction between measurement precision and time loss.
Solution Approach 2:
The patent changes the calibration parameter from multiple pressure points to a single resonant frequency measurement. By measuring the resonant frequency of the membrane at its current state after attachment, the system derives strain information without requiring time-consuming multi-point calibration, thus improving time efficiency while maintaining measurement precision.
2Measurement precision
If full recalibration over multiple calibration points is performed after attaching the pressure sensor IC device to a circuit board, then measurement precision is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent extracts only the essential calibration information needed by measuring just one resonant frequency of the membrane, rather than performing full recalibration over multiple calibration points. This extraction approach obtains the necessary strain compensation data with minimal time investment, resolving the contradiction between measurement precision and time loss.
Solution Approach 2:
The patent changes the calibration parameter from multiple pressure points to a single resonant frequency measurement. By measuring the resonant frequency of the membrane at its current state after attachment, the system derives strain information without requiring time-consuming multi-point calibration, thus improving time efficiency while maintaining measurement precision.
3Loss of time
If resonant frequency measurement and strain calculation method is used for recalibration, then loss of time and manufacturing cost are reduced, but measurement precision may be compromised
Solution Approach 1:
The patent introduces the resonant frequency of the membrane as an intermediary parameter to indirectly measure strain. Instead of directly measuring pressure at multiple points, the system measures the resonant frequency, which changes with strain, and uses this intermediate measurement to calculate calibration parameters. This intermediary approach maintains measurement precision while significantly reducing calibration time.
Solution Approach 2:
The patent changes the calibration parameter from multiple pressure points to a single resonant frequency measurement. By measuring the resonant frequency of the membrane at its current state after attachment, the system derives strain information without requiring time-consuming multi-point calibration, thus improving time efficiency while maintaining measurement precision.
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 approach allows for efficient recalibration of capacitive pressure sensor IC devices post-attachment to a circuit board with minimal error, making the process less costly and practical while maintaining accuracy.
Implementation Method 1
determining a resonant frequency of the membrane in response to the applied test signal
Implementation Method 2
a piezoresistive read-out, which employs the piezoresistive effect to detect strain on the sensor
Data Source
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AI summary
In an embodiment, a method for calibrating a pressure sensor device is disclosed. The method involves determining the resonant frequency of a membrane of the pressure sensor device after the pressure sensor device has been attached to a circuit board, calculating a change in the resonant frequency from a resonant frequency stored in memory, calculating strain of the membrane of the pressure sensor device from the change in resonant frequency, and calibrating the pressure sensor device based on a capacitance-to-pressure curve calculated using the strain of the membrane of the pressure sensor device.