Combined MEMS Sound Transducer and Pressure Sensor Package
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Solution Overview
Problem
The challenge is to integrate MEMS pressure sensors and MEMS sound transducers into a single package for consumer electronics without increasing the size of the device, while minimizing the risk of moisture and dust ingress and ensuring accurate pressure sensing despite the sound transducer's membrane attenuating pressure waves.
Innovation Solution
A combined sound transducer and pressure sensor package design featuring a plane substrate with two cavities, one for each component, where the MEMS sound transducer covers a through hole for fluid communication, and a transfer block provides an electric path between package pads and the components, with the fluid opening and pads positioned on opposite sides to optimize space usage and prevent signal attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a MEMS sound transducer and MEMS pressure sensor are housed in individual packages, then each component can be properly fitted with its own fluid channels, but this increases the assembly space requirements and costs
Solution Approach 1:
The patent combines a MEMS sound transducer and a MEMS pressure sensor into a single integrated package. The package includes a substrate with a first cavity housing the sound transducer and a second cavity housing the pressure sensor, sharing common structural elements like the substrate and sealing structures, thereby reducing overall assembly space while maintaining individual component functionality
Solution Approach 2:
The package structure serves multiple functions simultaneously: the substrate provides mechanical support for both cavities, the sealing structures protect both components, and the package housing integrates fluid channeling for both the sound transducer and pressure sensor, eliminating the need for separate packaging infrastructure
2Area of stationary object
If a combined sensor package is used to reduce assembly space, then space is optimized, but the package becomes bulky and difficult to install with proper fluid port positioning
Solution Approach 1:
The patent utilizes vertical stacking of cavities along the thickness direction of the substrate, with the first cavity positioned above the second cavity. This three-dimensional arrangement allows both components to be integrated in a compact footprint while maintaining access to fluid ports from different directions, solving the positioning complexity issue
3Power
If the MEMS sound transducer is mounted in front of the MEMS pressure sensor in the fluid path to provide back volume, then sound transducer performance is improved, but the sound transducer membrane attenuates pressure waves causing faulty pressure sensing
Solution Approach 1:
The patent divides the fluid path into separate segments: the sound transducer has its own fluid channel providing back volume for optimal acoustic performance, while the pressure sensor has a separate fluid channel that bypasses the sound transducer membrane. This segmentation allows both components to operate independently without interference, maintaining pressure sensing accuracy while preserving sound transducer performance
4Area of stationary object
If the fluid opening and package pads are positioned on opposite sides of the package to optimize space usage, then assembly space is reduced, but the electrical connection becomes more challenging
Solution Approach 1:
The patent introduces a transfer block as an intermediary component that facilitates electrical connections between the package pads on one side and the internal components on the other side. The transfer block includes conductive elements that extend through the substrate, providing reliable electrical pathways without requiring direct access to all connection points from the same side, thereby simplifying the manufacturing process despite the opposite-side positioning
Data Source
AI summary
A package includes a substrate having a first surface and an opposing second surface, a first cavity adjacent to the first surface of the substrate within the package, and a second cavity adjacent to the second surface of the substrate within the package, wherein the second cavity includes a fluid opening for allowing a fluid to enter the second cavity; a through hole in the substrate providing fluid communication between the first and second cavities; a MEMS sound transducer disposed in one of the first cavity or the second cavity; a MEMS pressure sensor disposed in the other one of the first cavity or the second cavity; and a discrete transfer block arranged on the substrate and configured to provide an electric path between the package pad and the MEMS sound transducer and the MEMS pressure sensor, wherein the transfer block is a discrete component separate from the substrate.