Microphone Backplate Extension for Drop Reliability
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Solution Overview
Problem
Conventional microphones suffer from low product yield due to breakage during drop tests, primarily at the backplate step structure, caused by gas discharge leading to concentrated stress.
Innovation Solution
The microphone design includes a backplate extension portion with a second through hole that allows for direct air discharge from the inner cavity, preventing stress buildup and breakage, along with a method involving silicon oxide deposition and etching to form the necessary cavities and holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the backplate step structure is used to support the fixing portion, then the structural stability is improved, but the drop reliability deteriorates due to gas discharge causing concentrated stress and breakage
Solution Approach 1:
The inner cavity is divided into a first inner cavity and a second inner cavity that are communicatively connected. The first inner cavity is configured to communicate with the back cavity through the leak hole, while the second inner cavity communicates with the first inner cavity. This segmentation allows gas to be discharged from the second inner cavity through the first through hole in the backplate, preventing gas accumulation and stress concentration at the backplate step structure, thereby improving drop reliability while maintaining structural stability.
Solution Approach 2:
The first inner cavity acts as an intermediary chamber between the back cavity and the second inner cavity. Gas from the back cavity passes through the leak hole into the first inner cavity, which then communicates with the second inner cavity. This intermediary structure provides a controlled pathway for gas discharge, preventing direct pressure buildup at the vulnerable backplate step structure while maintaining the necessary structural support.
2Ease of manufacture
If the through hole is arranged in the middle region of the backplate with backplate step structure, then the manufacturing is simplified, but the product yield deteriorates due to breakage at the backplate step structure
Solution Approach 1:
The inner cavity is segmented into two communicatively connected cavities. The first inner cavity receives gas from the back cavity through the leak hole, and the second inner cavity communicates with the first inner cavity and discharges gas through the first through hole in the backplate. This segmentation enables controlled gas discharge that prevents breakage at the backplate step structure, thereby improving product yield while maintaining manufacturing simplicity.
Solution Approach 2:
The gas discharge function is extracted from the traditional single cavity structure and implemented through a dedicated second inner cavity with its own discharge path through the first through hole. This extraction separates the gas discharge pathway from the structural support function of the backplate step structure, preventing stress concentration and breakage, thus improving product yield without complicating manufacturing.
3Device complexity
If the single inner cavity structure is used, then the device complexity is reduced, but the drop performance deteriorates due to stress concentration from gas discharge
Solution Approach 1:
The single inner cavity is segmented into a first inner cavity and a second inner cavity that are communicatively connected. The first inner cavity handles gas intake from the back cavity, while the second inner cavity handles gas discharge to the external environment. This segmentation distributes stress and prevents concentration at the backplate step structure, improving drop performance while adding only moderate structural complexity.
Solution Approach 2:
The first inner cavity serves as an intermediary between the back cavity and the second inner cavity. It receives gas through the leak hole and transfers it to the second inner cavity for discharge. This intermediary structure provides a controlled gas flow path that prevents direct pressure buildup at the backplate step structure, improving drop performance while maintaining reasonable device complexity.
Data Source
AI summary
Provided is a microphone, including a base having a back cavity, a diaphragm, a backplate electrode, and a backplate spaced from the diaphragm and defining an inner cavity jointly with the diaphragm. The diaphragm includes a vibration portion, a fixing portion, and a leak hole. The back cavity is communicated with the inner cavity through the leak hole. The backplate is provided with a first through hole. The inner cavity is communicated with outside through the first through hole. The backplate includes a backplate body and a backplate extension portion. The inner cavity includes a first inner cavity and a second inner cavity. The backplate extension portion is provided with a second through hole, and the second inner cavity is communicated with outside through the second through hole. A method for manufacturing the microphone is further provided. The technical solution has better drop performance.