MEMS Microphone Can Guard Ring Venting
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Solution Overview
Problem
MEMS microphone devices often experience geometric defects due to pressure build-up during the heating cycle, causing the can to tilt, rotate, or shift, which affects the device's performance and quality.
Innovation Solution
Incorporating a guard ring with a vent or semi-cutout around the microphone, coupled with a non-meltable adhesive like epoxy, which maintains the can and guard ring in position during reflow, preventing deformation by allowing pressure equalization through the gap or semi-cutout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the can is heated during the heating cycle, then the acoustic seal is formed and flux/solvents evaporate, but pressure builds up causing the can to tilt, rotate, and shift
Solution Approach 1:
The can is segmented by introducing a vent aperture that divides the sealed cavity into a pressurized interior and a vented exterior pathway, allowing pressure to escape while maintaining the acoustic seal at the port
Solution Approach 2:
The vent aperture acts as an intermediary pressure relief pathway between the sealed interior cavity and the exterior environment, mediating the pressure build-up by allowing controlled escape of evaporating flux and solvents
2Object-affected harmful factors
If the can is tightly sealed to enclose the microphone, then protection is improved, but pressure build-up during heating causes deformation
Solution Approach 1:
The can exhibits local quality differentiation where the port area maintains a tight acoustic seal for protection while the vent aperture provides a localized pressure relief pathway, combining sealed protection with pressure management
3Manufacturing precision
If non-meltable adhesive is used to secure the can, then positioning stability is improved, but the adhesive must withstand high reflow temperatures
Solution Approach 1:
The adhesive material parameters are changed by selecting a non-meltable adhesive with a glass transition temperature and melting point exceeding the reflow soldering temperature, enabling it to maintain bonding strength and positioning accuracy under high temperature conditions
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
This solution effectively prevents tilting and deformation of the can during the heating cycle, ensuring the MEMS device maintains its geometric integrity and performance, even when integrated into larger systems.
Implementation Method 1
allowing pressure equalization through the gap or semi-cutout
Implementation Method 2
coupled with a non-meltable adhesive like epoxy, which maintains the can and guard ring in position during reflow
Data Source
AI summary
Systems, apparatuses, and methods for manufacturing a microelectromechanical system (MEMS) device. The MEMS device includes a substrate, a cap, a microelectromechanical component, and a tag. The cap is coupled to the substrate such that the substrate and the cap cooperatively define an interior cavity. One of the substrate or the cap defines a port. The microelectromechanical component is disposed within the interior cavity. The tag is coupled to the substrate and an exterior surface of the cap to secure the cap to the substrate.