Micro Speaker Package Structure with Embedded Coil and Etch Stop
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Solution Overview
Problem
Traditional moving coil speakers are large and expensive, and while MEMS technology can reduce size and cost, there is a need for a micro moving coil speaker with improved performance and reliability for smaller electronic products.
Innovation Solution
A micro speaker package structure that includes a substrate with a hollow chamber, a diaphragm suspended over the chamber, a coil embedded in the diaphragm, an etch stop layer made of metal, a carrier board, and a package lid with permanent magnetic elements positioned to enhance frequency response and reliability, using MEMS technology for manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional moving coil speakers are used, then the speaker can achieve good performance, but the area and cost will be large
Solution Approach 1:
The patent replaces traditional mechanical speaker manufacturing with MEMS (Micro-Electro-Mechanical Systems) fabrication processes. The moving coil speaker is manufactured using semiconductor-compatible techniques including photolithography, electroplating, and wafer bonding, enabling miniaturization while maintaining performance. The speaker structure is integrated into a semiconductor substrate with precise control over geometric parameters.
Solution Approach 2:
The patent systematically optimizes geometric parameters of the speaker structure including coil wire diameter (5-20 μm), coil turn density, diaphragm thickness (1-10 μm), and cavity dimensions. These parameter changes enable the speaker to achieve good acoustic performance in a miniaturized form factor suitable for mobile devices.
2Area of stationary object
If MEMS process is used to manufacture moving coil speaker, then the area and cost will be reduced, but the performance and reliability need to be improved
Solution Approach 1:
The patent divides the speaker structure into functionally optimized segments: a suspended moving coil structure, a separate diaphragm layer, a permanent magnet array, and an acoustic cavity. This segmentation allows each component to be independently optimized for its specific function while maintaining compatibility with MEMS batch fabrication processes.
Solution Approach 2:
The patent employs composite material structures including electroplated copper coils on polyimide substrates, sputtered aluminum permanent magnets, and layered diaphragm materials. These composite structures provide the necessary mechanical, electrical, and magnetic properties required for high-performance miniaturized speakers.
3Ease of manufacture
If the coil is exposed during etching process, then the coil structure can be formed, but the coil may be damaged by etching
Solution Approach 1:
The patent applies a protective coating material over the coil structure before the substrate etching process. This preliminary protection step ensures that the coil is not damaged during subsequent etching operations to form the acoustic cavity, while still allowing the etching process to proceed to create the speaker structure.
Solution Approach 2:
The patent introduces a protective coating as an intermediary layer between the coil and the etching environment. This coating material serves as a barrier that prevents direct contact between the etchant and the coil, thereby protecting the coil integrity while allowing the necessary etching operations to complete the speaker structure.
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 results in a micro speaker with improved frequency response and reliability, enabling smaller, cost-effective batch production of high-performance micro speakers for electronic products.
Implementation Method 1
a coil embedded in the diaphragm
Implementation Method 2
The package lid has a lid opening that exposes a portion of the top surface of the diaphragm
Implementation Method 3
a first permanent magnetic element disposed on the carrier board and in the hollow chamber
Data Source
AI summary
A package structure of a micro speaker is provided. The package structure includes a substrate, a diaphragm, a coil, an etch stop layer, a carrier board, a permanent magnetic element, and package lid. The substrate has a hollow chamber. The diaphragm is suspended over the hollow chamber. The coil is embedded in the diaphragm. The etch stop layer is positioned below the coil and overlaps the coil in the direction that is perpendicular to the top surface of the diaphragm. The etch stop layer is made of a metal material. The carrier board is disposed on the bottom surface of the substrate. The permanent magnetic element is disposed on the carrier board and in the hollow chamber. The package lid is wrapped around the substrate and the diaphragm, and has a lid opening that exposes a portion of the top surface of the diaphragm.