Pressure Sensor Potential Adjustment Member ESD Protection
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Solution Overview
Problem
Liquid seal type pressure sensors are vulnerable to damage from electrostatic discharge (ESD) due to insufficient electrostatic withstand voltage, particularly around the semiconductor sensor chip, and existing solutions either increase costs or fail to prevent discharge effectively.
Innovation Solution
A pressure sensor design with a potential adjustment member having a modified shape, including a metal frame and shield plate, is implemented to increase the distance between the pressure detection element and the diaphragm and housing, ensuring a minimum insulating distance of 0.6 mm or more, and featuring a recessed component on the pressure chamber side to prevent discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the distance between the potential adjustment member and the housing/diaphragm is reduced, then the device complexity is reduced and manufacturing is easier, but discharge occurs between the potential adjustment member and housing/diaphragm damaging the pressure detection element
Solution Approach 1:
The potential adjustment member is designed with a recessed component that extends toward the pressure chamber, creating a three-dimensional configuration. This dimensional change allows the member to maintain adequate insulation distance from the housing and diaphragm while still providing effective electrostatic protection for the pressure detection element, thus resolving the contradiction between device simplicity and electrostatic protection reliability.
2Reliability
If an ESD protect circuit is integrated into the semiconductor sensor chip, then electrostatic protection is improved, but the unit price of the semiconductor sensor chip skyrockets and sufficient area is difficult to provide
Solution Approach 1:
The ESD protection function is extracted from the semiconductor sensor chip and implemented as a separate potential adjustment member. This external protection structure is formed independently of the chip fabrication process, eliminating the need for costly on-chip ESD circuits while maintaining effective electrostatic protection for the pressure detection element.
3Reliability
If adhesive is used to fill spaces between housing and lead pins, then electrostatic withstand voltage is increased, but discharge around the semiconductor sensor chip is not prevented
Solution Approach 1:
The potential adjustment member serves as an intermediary conductive structure that actively manages electrostatic protection. Unlike passive adhesive filling, this conductive member is specifically configured to shield the semiconductor sensor chip from discharge, creating a controlled electrostatic environment that prevents harmful discharge around the chip while maintaining high electrostatic withstand voltage.
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 modified shape of the potential adjustment member effectively prevents damage from static electricity and withstand voltage, maintaining the functionality of the pressure detection element while enhancing electrostatic protection without increasing the unit price of the sensor chip.
Implementation Method 1
a fluid pressure of a fluid in a pressure chamber acts on a diaphragm separating the pressure chamber from the liquid seal chamber and is transmitted to the pressure detection element via the sealing oil in the liquid seal member
Implementation Method 2
an internal circuit in a semiconductor sensor chip is disadvantageously damaged by Electro-Static Discharge (ESD)
Data Source
AI summary
A pressure sensor includes a diaphragm made of metal and configured to separate a pressure chamber from a liquid seal chamber, a housing made of metal and disposed around the liquid seal chamber, a pressure detection element disposed in the liquid seal chamber in a liquid . . . sealable manner to detect the pressure of the fluid, and a potential adjustment member disposed between the pressure detection element and each of the diaphragm and the housing and being conductive, the potential adjustment member being connected to a zero potential terminal of the pressure detection element, wherein a distance between the potential adjustment member and each of the diaphragm and the housing is larger than a predetermined insulating distance.