Frame-Free MEMS Microphone Bottom-Port Design
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Solution Overview
Problem
Conventional MEMS microphones with top-port package structures face high costs and complex manufacturing processes, which hinder their widespread adoption and acoustic performance.
Innovation Solution
A bottom-port MEMS microphone design for frame-free devices featuring a substrate with an acoustic sensor and pads, an ASIC chip, a metal cover, and a dustproof stratum reticulare, connected via a flexible circuit board, offering improved acoustic performance and simplified structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a top-port MEMS microphone package structure is used, then the manufacturing process is simplified, but the acoustic performance deteriorates and costs increase
Solution Approach 1:
The patent inverts the conventional top-port design to a bottom-port configuration. The sound hole is positioned at the bottom of the shell instead of the top, and the acoustic wave guide directs sound from the bottom upward to the acoustic sensor. This inversion resolves the contradiction by achieving both simplified manufacturing (through integrated substrate design) and improved acoustic performance (through optimized sound path)
Solution Approach 2:
The patent merges the circuit board and shell into a single integrated substrate structure. The substrate simultaneously serves as the mounting platform for electronic components (ASIC chip, MEMS chip) and as the acoustic wave guide structure with integrated sound holes. This merging simplifies the manufacturing process by reducing assembly steps while maintaining acoustic performance through optimized sound transmission paths
2Device complexity
If a top-port MEMS microphone package structure is used, then the structure is simpler, but the manufacturing costs increase and process difficulty increases
Solution Approach 1:
The patent combines multiple functions into the substrate: structural support, acoustic wave guiding, and sound hole formation. The substrate integrates the circuit board and shell functions, eliminating separate manufacturing and assembly steps for these components, thereby reducing overall manufacturing complexity and cost despite maintaining structural simplicity
3Device complexity
If sound holes are disposed on the shell (top-port), then the structure is simplified, but the acoustic performance worsens
Solution Approach 1:
The patent inverts the sound hole positioning from the conventional top-port configuration to a bottom-port configuration. Sound holes are positioned at the bottom of the shell, and the acoustic wave guide directs sound upward to the sensor. This inversion improves acoustic performance by optimizing the sound transmission path while maintaining structural simplicity through the integrated substrate design
4Ease of manufacture
If a conventional MEMS microphone with separate cavity structure is used, then the assembly is straightforward, but the device size increases and integration difficulty increases
Solution Approach 1:
The patent merges the cavity structure into the substrate itself rather than using a separate enclosure. The substrate's recess regions form the cavities needed for component mounting, eliminating the need for separate shell and cavity assemblies. This reduces overall device size while maintaining assembly straightforwardness through the integrated design
Solution Approach 2:
The patent implements nested integration where the MEMS chip and ASIC chip are mounted within recess regions of the substrate, which itself is integrated with the acoustic wave guide and sound hole structures. This nested arrangement maximizes space utilization, reducing device volume while keeping the assembly process straightforward
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 enhances acoustic performance and simplifies the manufacturing process, making MEMS microphones more suitable for high-tech applications like smartphones and cameras, while reducing costs and complexity.
Implementation Method 1
a first substrate region provided with an acoustic sensor, and a second substrate region provided with a plurality of pads
Data Source
AI summary
A MEMS microphone for a frame-free device, comprising a substrate, wherein the substrate comprises a first substrate region provided with an acoustic sensor, an ASIC chip, and a MEMS chip, and a second substrate region provided with a plurality of pads; both the first substrate region and the second substrate region are disposed at the same side of the substrate; an acoustic through-hole is disposed at the back of the first substrate region; a microphone connection structure further comprises a flexible circuit board, wherein the flexible circuit board electrically connects the plurality of pads of the MEMS microphone to a circuit board of the frame-free device; the acoustic through-hole is aligned with an acoustic opening of the frame-free device; by adopting the MEMS microphone for a frame-free device, the MEMS microphone may be more widely used in many high-tech industries and has better acoustic performance over the conventional MEMS microphone.