MEMS Microphone Conductive Case Shielding
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Solution Overview
Problem
Existing MEMS microphones are vulnerable to physical damage, light interference, and electromagnetic interference due to their fragile nature and lack effective shielding, which increases production costs and reliability issues with thin conductive layers used for protection.
Innovation Solution
A MEMS microphone design featuring a conductive case covering the housing and cover, forming a cavity with a conductive shield that sits on a step, providing protection akin to a Faraday cage, and using ceramic materials with embedded conductive traces for electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If thin conductive layers are electroplated on non-conductive layers for shielding, then electromagnetic shielding is provided, but production cost increases and the layers peel off
Solution Approach 1:
The patent replaces the electroplating process (mechanical/chemical deposition) with a ceramic molding process where conductive traces are embedded within the ceramic housing material itself. This substitution eliminates the peeling issue by integrating the conductive elements into the structural material through embedding rather than surface deposition.
Solution Approach 2:
The patent uses composite materials by combining ceramic material with embedded conductive traces (such as metal particles or conductive ink) within the ceramic matrix. This creates a unified composite structure where the conductive elements are permanently integrated into the ceramic housing, providing both structural integrity and electromagnetic shielding without the peeling problems of separate layers.
2Object-affected harmful factors
If thin conductive layers are used for shielding, then electromagnetic protection is achieved, but production cost increases
Solution Approach 1:
The patent merges the shielding function with the housing structure by embedding conductive traces directly into the ceramic housing during the molding process. This consolidation eliminates the need for separate shielding components and complex multi-step assembly processes, thereby reducing production costs while maintaining effective electromagnetic protection.
Solution Approach 2:
The patent replaces the expensive and complex electroplating process with a more cost-effective ceramic molding process that embeds conductive traces. This substitution simplifies manufacturing, reduces material waste, and lowers production costs while achieving the same or better shielding effectiveness.
3Volume of moving object
If transducers are exposed without shielding, then device size is reduced, but transducers are vulnerable to physical damage and interference
Solution Approach 1:
The patent makes the ceramic housing serve multiple functions simultaneously: it provides the structural enclosure for the device, protects the transducers from physical damage, and embeds conductive traces to provide electromagnetic shielding. This multi-functionality allows comprehensive protection without significantly increasing device size, as all protective functions are integrated into a single component.
Solution Approach 2:
The patent implements nesting by embedding the conductive shielding traces within the ceramic housing material itself, and then placing the transducers inside the enclosed cavity formed by this protective housing. This nested structure provides layered protection (ceramic enclosure + embedded conductive shielding) while maintaining a compact form factor.
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 solution effectively shields transducers from interference signals, enhancing durability and reducing production costs by ensuring the conductive case is securely fixed and providing reliable electromagnetic shielding.
Implementation Method 1
The MEMS microphone further includes a conductive case covering the cover and the sidewall, with a bottom end of the conductive case sitting on the step. By virtue of the conductive case, the transducers in the cavity can be protected against the interference signals such as RFI signals, much like a Faraday cage.
Implementation Method 2
a moveable diaphragm separated from the backplate for forming a capacitor. While external sound waves reach the diaphragm, the diaphragm will be activated to vibrate relative to the backplate, which changes the distance between the diaphragm and the backplate and changes the capacitance value. As a result, the sound waves are converted into electrical signals.
Data Source
AI summary
A MEMS microphone includes a cover, a housing engaging with the cover for forming a cavity. The housing includes a base and a sidewall extending perpendicularly from the base. A conductive case is provided to cover the cover and the sidewall of the housing. The base defines a periphery portion outside of the cavity for forming a step, and the conductive case locates a bottom end thereof on the step.