MEMS Pressure Sensor Packaging with Electrostatic Overload Protection
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Solution Overview
Problem
Current MEMS pressure sensor packaging structures are simple and lack functionality, failing to provide adequate protection against pressure overload, which can damage the sensing chip and hinder effective pressure detection.
Innovation Solution
A packaging structure for MEMS pressure sensors that includes a film forming a sealing chamber with a sensing medium and a pressure sensor chip, a sealing cover suspended on one side of the film, and electrodes connected to both the film and the sealing cover, allowing for electrostatic attraction to balance overloaded pressures through voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple packaging structure is used for the MEMS pressure sensor, then the manufacturing complexity is reduced, but the sensor chip cannot be protected against pressure overload damage
Solution Approach 1:
The packaging structure introduces a dynamic electrostatic balance mechanism that activates under pressure overload conditions. The sealing cover can move relative to the sensing chip, and the electrostatic attraction force dynamically adjusts to counterbalance excessive pressure, transforming a static structure into a dynamically responsive protective system.
Solution Approach 2:
The invention changes the physical state and parameters of the packaging system by introducing electrostatic fields. By applying voltage to generate electrostatic attraction between the sealing cover and sensing chip, the system transitions from a passive mechanical structure to an active electromechanical system capable of force balancing.
2Strength
If the sealing chamber is made rigid to protect the sensor chip, then the structural strength is improved, but the pressure transmission function is compromised
Solution Approach 1:
The sealing cover acts as a flexible element that can deform under pressure while maintaining structural integrity. This flexibility allows the sealing chamber to transmit pressure changes to the sensing chip while the electrostatic force provides the necessary structural support to prevent collapse under overload conditions.
Solution Approach 2:
The packaging structure combines mechanical structural elements (sealing chamber walls) with electrostatic field elements (charged sealing cover and electrode). This composite approach integrates mechanical strength with electrostatic force generation, allowing the system to simultaneously provide structural support and pressure transmission.
3Device complexity
If no overload protection mechanism is added, then the device complexity remains low, but the sensing chip is vulnerable to damage from excessive pressure
Solution Approach 1:
The electrostatic balance mechanism provides preliminary protection by generating counteracting electrostatic force before the pressure overload can cause damage to the sensing chip. The system is pre-configured with electrodes and charging capability to immediately respond to excessive pressure conditions.
Solution Approach 2:
The sealing cover serves as an intermediary element between the external pressure environment and the sensing chip. It transmits normal pressure changes while the electrostatic force acts as a mediating protective force that prevents excessive pressure transmission to the vulnerable chip.
4Measurement precision
If the film is made highly elastic to transmit pressure effectively, then the pressure transmission efficiency is improved, but the film becomes more susceptible to damage under overload
Solution Approach 1:
The electrostatic attraction force acts as a counterbalancing force that opposes the excessive pressure load on the film. This electrostatic 'counterweight' supports the film during overload conditions, allowing the film to remain highly elastic for normal pressure transmission while being protected from damage during extreme conditions.
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 proposed solution effectively protects the sensing chip from damage due to pressure overload by generating electrostatic attraction between the film and the sealing cover, ensuring accurate pressure detection and extending the device's operational lifespan.
Implementation Method 1
when the external pressure increases, the film bends towards an inner side of the sealing chamber to cause the sealing chamber to contract and transmit pressure to the pressure sensor chip through the sensing medium
Implementation Method 2
in a case that voltages access the sealing cover and the film through the corresponding electrodes, an electrostatic attraction is generated between the sealing cover and the film to balance an overloaded pressure
Data Source
AI summary
The present application discloses a packaging structure and method of an MEMS pressure sensor. The packaging structure of the MEMS pressure sensor includes: a film, forming a sealing chamber with a base, during manufacturing the sealing chamber is internally equipped with a sensing medium and a pressure sensor chip, when the external pressure increases, the film bends towards an inner side of the sealing chamber to cause the sealing chamber to contract and transmit pressure to the pressure sensor chip through the sensing medium. The packaging structure of the present application can avoid the sensing chip from being damaged by excessive contraction of the sealing chamber due to pressure overload, and thus achieves overload protection.