Packaged Microphone with Enlarged Back Volume
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Solution Overview
Problem
Conventional microphone packages face challenges in optimizing signal quality and sensitivity due to limited space, particularly in compact applications like hearing aids, where it is difficult to arrange the microphone package to face the direction of sound propagation without occupying excessive space.
Innovation Solution
The design incorporates a packaged microphone with an enlarged back volume and fluid communication between two cavities, utilizing additional back volume apertures and a side port to enhance sensitivity and performance without sacrificing space, allowing for improved sound wave detection and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the microphone package is made compact for applications like hearing aids, then the device size is reduced, but the back volume is limited which reduces signal quality and sensitivity
Solution Approach 1:
The package is divided into two separate cavities (first cavity containing the MEMS microphone, second cavity providing additional back volume) that are fluidly connected. This segmentation allows each cavity to serve a specific function while collectively providing the necessary back volume for optimal performance in a compact overall package size.
Solution Approach 2:
The invention utilizes the third dimension by stacking cavities vertically (one above the other) rather than expanding horizontally. The first lid is coupled to the first side of the substrate and the second lid is coupled to the second side, creating a layered structure that maximizes back volume within a compact footprint suitable for hearing aid applications.
2Measurement precision
If the back volume is increased to improve signal quality, then the sensitivity is enhanced, but the package occupies more space
Solution Approach 1:
The second cavity is positioned beneath the first cavity and is fluidly connected through back volume apertures in the substrate. This nested arrangement allows the second cavity to provide additional back volume that is acoustically coupled to the first cavity, effectively increasing the total back volume without proportionally increasing the external package dimensions.
Solution Approach 2:
The invention exploits the vertical dimension by creating a second cavity beneath the substrate rather than expanding the cavities laterally. This approach increases back volume by utilizing the thickness dimension of the package, allowing for enhanced signal quality while maintaining a compact planar footprint.
3Device complexity
If conventional single-cavity packages are used, then the structure is simple, but the back volume is insufficient for optimal performance
Solution Approach 1:
The single cavity is segmented into two separate cavities (first and second cavities) that are fluidly connected through back volume apertures. This segmentation allows the package to achieve greater total back volume while maintaining a modular structure that can be integrated into compact devices.
Solution Approach 2:
The first and second cavities are merged through fluid communication via back volume apertures in the substrate, creating a combined acoustic volume that is greater than either cavity alone. This merging of separate cavity spaces provides increased back volume while keeping individual cavity structures relatively simple.
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
This configuration optimizes signal quality and sensitivity by increasing the back volume within the microphone package, enabling effective sound wave detection and processing while maintaining a compact form factor, suitable for applications like hearing aids.
Implementation Method 1
the first and second cavities are fluidly connected
Data Source
AI summary
A packaged integrated device includes a package substrate having a first surface and a second surface opposite the first surface, and the package substrate has a hole therethrough. The integrated device package also includes a first lid mounted on the first surface of the package substrate to define a first cavity, and a second lid mounted on the second surface of the package substrate to define a second cavity. A microelectromechanical systems (MEMS) die can be mounted on the first surface of the package substrate inside the first cavity and over the hole. A port can be formed in the first lid or the second lid.