MEMS Microphone Anti-Adhesion Structure for Diaphragm Impact Stress
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Solution Overview
Problem
Existing MEMS microphones suffer from diaphragm breakage due to stress concentration at dimple positions under repeated impact, leading to potential breakage of both the diaphragm and back plate.
Innovation Solution
Incorporation of an elastically deformable anti-adhesion member between the diaphragm and back plate, which cushions the diaphragm's movement to prevent stress concentration and breakage by allowing it to move away when the restoring force exceeds sound and electric field forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dimple structure is arranged on the back plate to prevent short-circuiting, then the risk of membrane absorption is reduced, but stress concentration occurs at the dimple positions leading to diaphragm breakage under repeated impact
Solution Approach 1:
The patent introduces an anti-adhesion layer as an intermediary substance between the diaphragm and back plate. This layer prevents direct contact and short-circuiting while distributing stress uniformly across the diaphragm surface, eliminating the stress concentration problem caused by dimple structures. The anti-adhesion layer serves as a mediator that fulfills both the electrical isolation function and the mechanical stress distribution function.
Solution Approach 2:
The patent extracts the harmful dimple structure from the back plate and replaces it with a continuous anti-adhesion layer. By removing the localized dimple features that cause stress concentration, the solution eliminates the source of the problem while maintaining the necessary anti-adhesion and electrical isolation functions through a different structural approach.
2Measurement precision
If the diaphragm moves close to the back plate under sound pressure, then the capacitance changes to convert sound signal, but contact between diaphragm and back plate causes short-circuiting
Solution Approach 1:
The anti-adhesion layer acts as a mediator that prevents direct contact between the diaphragm and back plate while allowing the diaphragm to move freely in response to sound pressure. This maintains the capacitance change mechanism for sound signal conversion while eliminating the short-circuit risk through continuous electrical isolation.
Solution Approach 2:
The patent applies preliminary anti-action by pre-establishing the anti-adhesion layer before any contact can occur. This preventive measure ensures that the diaphragm and back plate can never come into direct contact, thereby preemptively eliminating the short-circuit risk while preserving the full range of diaphragm motion for accurate sound signal conversion.
3Reliability
If dimples are arranged on the diaphragm to prevent contact, then short-circuiting is avoided, but pits are left on the back plate leading to potential breakage
Solution Approach 1:
The anti-adhesion layer serves as a mediator that eliminates the need for dimple structures on either the diaphragm or back plate. By providing a continuous barrier, it prevents contact while avoiding the creation of pits or localized weak points that would compromise the structural integrity of the back plate.
Solution Approach 2:
The patent applies local quality by using a uniform anti-adhesion layer with consistent properties across the entire surface, rather than localized dimple structures. This ensures that the anti-adhesion function is distributed evenly without creating localized stress concentrations or structural weaknesses in the back plate.
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
Prevents diaphragm breakage by distributing stress uniformly and maintaining continuous movement, thereby enhancing the reliability and longevity of the MEMS microphone.
Implementation Method 1
the anti-adhesion member is elastically deformable along a vibrating direction of the diaphragm
Implementation Method 2
thereby causing changes in capacitance between the diaphragm and the back plate and converting a sound signal into an electrical signal
Data Source
AI summary
An MEMS microphone includes a substrate with a back cavity and a capacitor system arranged on the substrate. The capacitor system includes a back plate and a diaphragm opposite to and spaced apart from the back plate. Surface of the back plate facing diaphragm or surface of diaphragm facing the back plate being provided with an anti-adhesion member. When the diaphragm moves until the anti-adhesion member is in contact with the diaphragm and the back plate at the same time, the anti-adhesion member is elastically deformable along a vibrating direction of the diaphragm. The anti-adhesion member of the present disclosure is elastic and may provide cushioning for movement of the diaphragm, which prevents rapid concentration of stress at a position of the diaphragm in contact with the anti-adhesion member, thereby preventing formation of pits in the diaphragm and preventing breakage of the diaphragm under repeated impact of the anti-adhesion member.