MEMS Microphone Package Conductive Casing EMI Shielding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing micromachined MEMS microphone packaging methods fail to effectively address issues such as acoustic leakage, secure attachment to PCB boards, electromagnetic interference shielding, signal transmission distortion, and ease of manufacturing for mass production.
Innovation Solution
A MEMS microphone package design featuring a conductive casing connected to a common analog ground lead on a PCB board, with a substrate and cover forming a cavity that minimizes acoustic alteration and includes an acoustic absorption layer to reduce noise, and a method for fabricating this package that ensures strong bonding and shielding from environmental interferences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional packaging methods are used for MEMS microphones, then the packaging process is simple, but acoustic leakage occurs and electromagnetic interference shielding is insufficient
Solution Approach 1:
The patent implements a nested package structure where the MEMS microphone die is housed within a cavity formed in a substrate, which is then enclosed by a cover. The substrate itself is mounted on a PCB board, creating multiple nested levels of protection. This nesting approach provides acoustic sealing and EMI shielding without requiring an entirely new package design, thus improving reliability while controlling complexity.
Solution Approach 2:
The patent employs composite material construction for the package housing, combining different materials with complementary properties. The substrate and cover are made from materials that provide both acoustic sealing and electromagnetic interference shielding capabilities. This use of composite materials allows simultaneous achievement of acoustic signal integrity and EMI protection without excessive structural complexity.
2Ease of manufacture
If the microphone package is designed for surface mounting, then assembly cost is reduced, but bonding strength to PCB board may be insufficient
Solution Approach 1:
The patent incorporates preliminary bonding structures during the packaging process. The substrate is designed with pre-formed bonding interfaces and mounting features that enable direct surface mounting to the PCB board. By preparing these bonding structures in advance during package fabrication, the design achieves both ease of manufacture through surface mounting and sufficient bonding strength without requiring complex secondary assembly operations.
3Object-affected harmful factors
If the package provides comprehensive EMI shielding, then electromagnetic interference is reduced, but acoustic signal distortion may increase
Solution Approach 1:
The patent applies local quality principles by providing EMI shielding specifically in regions where electromagnetic interference is most problematic, rather than uniformly throughout the entire package. The substrate and cover are designed with conductive shielding layers positioned to protect the sensitive MEMS die and signal paths, while maintaining acoustic transparency in the regions where sound needs to pass through. This localized approach reduces EMI without causing acoustic signal distortion.
4Productivity
If mass production methods are used, then productivity increases, but manufacturing precision may be compromised
Solution Approach 1:
The patent employs segmentation by dividing the packaging process into discrete, standardized stages that can be independently optimized for both precision and productivity. The package is designed as an assembly of separate components (substrate, cover, MEMS die) that can be manufactured and prepared separately using high-precision wafer-level processing, then assembled in a standardized final packaging step. This segmentation allows each stage to be optimized for mass production while maintaining overall manufacturing precision through standardized interfaces and tolerances.
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 reduces acoustic leakage, enhances bonding strength, shields against electromagnetic interference, and minimizes signal distortion, while allowing for mass production and surface mounting, maintaining acoustic signal integrity and mechanical protection.
Implementation Method 1
an acoustic absorption layer to reduce noise
Implementation Method 2
a conductive casing disposed enclosing the top cover part and the housing wall, wherein the conductive casing is soldered to a PCB board and is electrically connected to a common analog ground lead on the PCB board
Data Source
AI summary
MEMS microphone packages and fabrication methods thereof are disclosed. One method for fabricating a MEMS microphone package, includes providing a substrate, forming a cavity enclosed by a top cover part, wherein a housing wall part surrounds and supports the top cover part, and the substrate supports the housing wall part and the cover part, forming a MEMS sensing element and an IC chip inside the cavity, forming an opening comprising an acoustic passage connecting the cavity to an ambient space, and forming a conductive casing enclosing the top cover part and the housing wall, wherein the conductive casing is soldered to a PCB board and is electrically connected to a common analog ground lead on the PCB board.