Stacked PCB MEMS Microphone Package with Metal Cap
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
MEMS microphone packaging faces challenges in providing a sufficient back chamber for optimal performance while protecting the device from environmental hazards, as existing methods either result in inadequate back chambers or expose the device to external threats, and often utilize expensive materials.
Innovation Solution
A method involving a stacked PCB package with a metal cap structure that surrounds the MEMS acoustic sensor and electronic components, where the opening for external fluid and acoustic energy is not aligned with the sensor, forming a back chamber within the PCB stack to ensure protection and functionality, and using cost-effective materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a 2-layer PCB substrate with metal lid is used to provide environmental protection, then the device is protected from external hazards, but the back chamber becomes insufficient
Solution Approach 1:
The package is divided into multiple functional layers: a first PCB layer for mounting the MEMS device and providing partial back chamber space, and a second PCB layer stacked underneath to extend the back chamber volume. This segmentation allows the package to provide both environmental protection and sufficient back chamber volume that cannot be achieved with a single 2-layer structure.
2Object-affected harmful factors
If the opening is positioned away from the MEMS device to provide environmental protection, then protection is improved, but the back chamber becomes insufficient
Solution Approach 1:
Instead of relying solely on lateral positioning of the opening away from the MEMS device, the solution extends into the vertical dimension by stacking a second PCB layer underneath the first layer. This dimensional transition creates additional back chamber volume while maintaining the protective offset positioning of the opening.
3Volume of stationary object
If a multi-layer PCB is used to create the required back chamber, then the back chamber volume is sufficient, but the cost increases
Solution Approach 1:
The second PCB layer serves multiple functions simultaneously: it extends the back chamber volume, provides additional environmental protection, and offers a mounting surface for electronic components. This multi-functionality achieves sufficient back chamber volume without requiring expensive specialized packaging materials, using instead standard PCB manufacturing processes.
4Volume of moving object
If a flexible substrate with folding process is used, then the package is compact, but the MEMS die is exposed to external environmental hazards
Solution Approach 1:
The MEMS device is nested within a protective enclosure formed by the stacked PCB layers and metal cap. The first PCB layer provides immediate protection, while the second PCB layer and metal cap provide additional layers of protection, creating a nested protective structure that shields the MEMS die from environmental hazards while maintaining compact dimensions.
Data Source
AI summary
A MEMS microphone with a stacked PCB package is described. The MEMS package has at least one MEMS acoustic sensor device located on a PCB stack. A metal cap structure surrounds the at least one MEMS acoustic sensor device wherein an edge surface of the metal cap structure is attached and electrically connected to the PCB stack. In a first embodiment, a back chamber is formed underlying the at least one MEMS acoustic sensor device and within the PCB stack wherein an opening underlying the at least one MEMS acoustic sensor device accesses the back chamber. An opening in the metal cap structure not aligned with the at least one MEMS acoustic sensor device allows external fluid, acoustic energy or pressure to enter the at least one MEMS acoustic sensor device. In a second embodiment, a back chamber is formed in the space under the metal cap and over the first PCB. A hollow chamber is formed between the first PCB and the second PCB wherein an opening under the at least one MEMS acoustic sensor device accesses the hollow chamber. An opening in a bottom surface of the PCB stack not aligned with the at least one MEMS acoustic sensor device also accesses the hollow chamber and allows external fluid, acoustic energy or pressure to enter the at least one MEMS acoustic sensor device.