PCB Speaker Diaphragm Micromachining for Cost Reduction
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Solution Overview
Problem
Conventional miniaturized speakers face challenges in size reduction due to complex manufacturing processes and fragile materials, leading to high costs and poor reliability, with MEMS technology being costly and inefficient.
Innovation Solution
A method for micromachining a speaker diaphragm on a PCB substrate involves providing metal paths and through holes, a patterned sacrificial layer, and a diaphragm layer that is deposited and connected to the metal paths, with the sacrificial layer being released to form a corrugated diaphragm, reducing production costs and improving sound pressure and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional MEMS speaker manufacturing process is used, then miniaturization is achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent merges the speaker diaphragm manufacturing with the PCB substrate manufacturing process. The diaphragm is formed by depositing and patterning metal layers directly on the PCB substrate using the same photolithography and etching processes, eliminating the need for separate MEMS wafer fabrication and magnet integration steps. This integration significantly reduces manufacturing complexity while achieving miniaturization.
Solution Approach 2:
The PCB substrate serves multiple functions: it acts as both the structural support for the speaker and the diaphragm material itself. The metal traces on the PCB serve dual purposes as both electrical connection paths and as part of the diaphragm structure. This multi-functionality reduces the number of components and manufacturing steps required.
2Volume of moving object
If conventional MEMS speaker manufacturing is used, then miniaturization is achieved, but manufacturing cost increases
Solution Approach 1:
By combining the speaker diaphragm fabrication with the existing PCB manufacturing process, the patent eliminates the need for expensive separate MEMS fabrication facilities and equipment. The diaphragm is created using standard PCB deposition and etching processes that are already optimized for high-volume production, significantly reducing manufacturing cost while achieving small speaker sizes.
Solution Approach 2:
The patent uses a sacrificial layer (such as photoresist or dry film) that is temporarily applied during manufacturing and then removed. This sacrificial layer enables precise pattern transfer but is discarded after use, simplifying the manufacturing process and reducing the need for expensive reusable tooling or complex release mechanisms.
3Volume of moving object
If conventional MEMS speaker is used, then miniaturization is achieved, but reliability deteriorates due to fragile materials
Solution Approach 1:
The patent creates a composite structure where the diaphragm consists of multiple metal layers (such as copper and aluminum) deposited on the PCB substrate. These layers are bonded together through electroplating or lamination, creating a mechanically robust composite material that is both flexible enough for vibration and strong enough to withstand handling and assembly, thereby improving reliability.
Solution Approach 2:
The patent introduces a corrugated or curved structure to the diaphragm by forming undulating patterns in the metal layers during the patterning process. This curvature provides structural reinforcement while maintaining the flexibility needed for vibration, preventing the diaphragm from breaking under stress and improving overall reliability.
4Volume of moving object
If conventional MEMS speaker is used, then miniaturization is achieved, but performance deteriorates due to limited diaphragm displacement
Solution Approach 1:
The corrugated structure of the diaphragm allows for larger displacement amplitude during vibration while maintaining structural integrity. The undulating pattern acts as a mechanical amplifier, enabling the small diaphragm to move more air and generate higher sound pressure levels despite its miniaturized size.
Solution Approach 2:
The multi-layer metal composite structure provides optimized mechanical properties with different layers contributing different characteristics. The copper layer provides structural strength while the aluminum layer provides flexibility, allowing the diaphragm to achieve large excursions without breaking, thereby improving sound pressure output.
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 method lowers production costs and enhances sound pressure by allowing larger diaphragm deflection under lower stress, improving the reliability and acoustic performance of the speaker.
Implementation Method 1
the sacrificial layer is released by etching, stripping or dissolving followed by drying
Implementation Method 2
the sacrificial layer is released by etching, stripping or dissolving followed by drying
Implementation Method 3
providing a diaphragm layer on the sacrificial layer through depositing, mounting or laminating
Data Source
AI summary
Provided is a PCB speaker and a method for micromachining the speaker diaphragm on PCB substrate, the method for micromachining the speaker diaphragm on PCB substrate comprises: providing metal paths and at least one through hole on the PCB substrate; providing a patterned sacrificial layer on the PCB substrate, the sacrificial layer covering all the through holes on the PCB substrate; providing a diaphragm layer on the sacrificial layer through depositing, mounting or laminating, the diaphragm layer covering the sacrificial layer and electrically connected with the metal paths on the PCB substrate, thereby forming a diaphragm layer; and releasing the sacrificial layer and the diaphragm layer remains. With the micromachining method for the above PCB substrate and the diaphragm, the production cost of the speaker can be lowered, and the reliability of the product can be improved at the same time.