Non-Planar MEMS Microphone Substrate Sidewall Reinforcement
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Solution Overview
Problem
Conventional MEMS microphone package structures face challenges in thinning the substrate without compromising structural strength, which limits the capacity of the back chamber and acoustic performance.
Innovation Solution
A non-planar substrate with a reinforced sidewall allows for thinning of the carrying bottom portion while maintaining structural integrity, combined with a cover plate that electrically connects to the sidewall to shield electromagnetic interference and increase the back chamber capacity without altering the microphone's dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the substrate thickness is increased to maintain structural strength, then the structural strength is improved, but the back chamber capacity is reduced
Solution Approach 1:
The substrate is transformed from a planar two-dimensional structure to a non-planar three-dimensional structure with a sidewall. This dimensional change allows the substrate to gain structural strength from the vertical sidewall reinforcement while maintaining a thin carrying bottom portion, thereby increasing back chamber capacity without sacrificing structural integrity.
Solution Approach 2:
The substrate incorporates a curved or angled sidewall structure instead of a flat planar design. This curvature provides structural reinforcement through geometric shape, allowing the substrate to withstand mechanical stress while maintaining minimal thickness in the carrying area, thus resolving the contradiction between strength and volume.
2Volume of stationary object
If the substrate thickness is decreased to increase back chamber capacity, then the back chamber capacity is improved, but the structural strength is reduced
Solution Approach 1:
By adding a vertical sidewall dimension to the substrate structure, the design achieves structural reinforcement without increasing the horizontal footprint or thickness of the carrying bottom portion. This allows the substrate to be thinned for increased back chamber capacity while the sidewall provides the necessary structural strength.
Solution Approach 2:
The substrate is divided into functionally distinct segments: a thin carrying bottom portion for acoustic performance and a separate sidewall structure for structural reinforcement. This segmentation allows each part to be optimized independently - the bottom portion can be thinned to increase back chamber capacity while the sidewall maintains structural integrity.
3Ease of manufacture
If a planar substrate is used to simplify manufacturing, then the ease of manufacture is improved, but the back chamber capacity is limited
Solution Approach 1:
The manufacturing process is extended to incorporate a third dimension by forming a sidewall structure on the substrate. This additional dimensional feature, while increasing manufacturing complexity, enables the substrate to provide both structural reinforcement and increased back chamber capacity, justifying the added manufacturing steps through significant performance benefits.
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 design enhances the acoustic performance by increasing the back chamber capacity, maintaining structural strength, and providing electromagnetic interference shielding, while simplifying the manufacturing process and reducing production costs.
Implementation Method 1
The sidewall electrically connects to the top surface of the carrying bottom portion by a first metal layer
Implementation Method 2
A second metal layer on the cover plate is electrically connected to the first metal layer to shield electromagnetic interference
Data Source
AI summary
A MEMS microphone package structure having a non-planar substrate includes the non-planar substrate, a cover plate, and a sound wave transducer. The non-planar substrate has a carrying bottom portion and a sidewall. The carrying bottom portion has a sound hole. The cover plate covers the non-planar substrate from above and connects to the sidewall. Both the cover plate and the sidewall have a metal layer for shielding the microphone from electromagnetic interference. The sound wave transducer is located corresponding to the sound hole. Hence, the sidewall reinforces the non-planar substrate, such that the carrying bottom portion is thinned without weakening the non-planar substrate, so as to increase the capacity of a back chamber of the microphone without changing the appearance and dimensions of the package structure.