Substrate GND Pad for Reverse Sound Hole MEMS Microphone ESD Protection
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Solution Overview
Problem
MEMS microphones, particularly reverse sound hole type, are vulnerable to electrostatic discharge (ESD) due to exposed sound collectors, and existing substrates lack effective countermeasures, leading to design constraints and increased costs when trying to prevent static electricity exposure.
Innovation Solution
A substrate with a substrate sound hole communicating with the MEMS microphone's sound hole and a GND pad surrounding the substrate sound hole, which directs static electricity to ground, enhancing ESD protection without additional parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reverse sound hole type MEMS microphone is used with an exposed sound collector, then the sound collecting function is achieved, but the microphone becomes vulnerable to electrostatic discharge (ESD)
Solution Approach 1:
The invention utilizes the substrate ground land and ceiling terminal, originally intended only for acoustic coupling, to also serve as ESD protection pathways. By routing static electricity through these existing ground connections to the chassis ground, the design converts a potential harm (ESD exposure) into a protected state without requiring additional protective components.
Solution Approach 2:
The ground land and ceiling terminal are designed to perform dual functions: maintaining acoustic coupling between the substrate sound hole and MEMS sound hole, and providing ESD protection pathways. This multi-functionality eliminates the need for separate protection structures while ensuring both acoustic performance and electrostatic safety.
2Reliability
If a sound conduit or mesh is added to protect the MEMS microphone from static electricity, then ESD protection is achieved, but design constraints increase and costs rise due to additional parts
Solution Approach 1:
The invention merges the ESD protection function with the existing acoustic coupling structure (ground land and ceiling terminal). Instead of adding separate protection components like sound conduits or meshes, the design integrates electrostatic protection pathways into the already-necessary acoustic elements, thereby reducing overall device complexity and part count.
Solution Approach 2:
The substrate ground land and ceiling terminal serve themselves by performing both acoustic coupling and ESD protection functions. The existing structural elements automatically provide protection without requiring additional dedicated protection components, making the system self-sufficient and reducing design complexity.
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 substrate effectively prevents ESD diffusion to the MEMS microphone, maintaining stable acoustic characteristics and avoiding design constraints and cost increases, while allowing for more flexible design options.
Implementation Method 1
The GND pad is disposed around the substrate sound hole on another surface of the substrate
Data Source
AI summary
The present invention provides a substrate that is highly resistant to ESD, on which a reverse sound hole type MEMS microphone can be mounted. The substrate has one surface connected to a MEMS microphone, and comprises a substrate sound hole that penetrates through the substrate and communicates with a sound hole of the MEMS microphone, and a GND pad disposed around the substrate sound hole on another surface of the substrate.