Stacked MEMS Microspeaker Package with Connected Acoustic Cavities
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Solution Overview
Problem
Micro sound producing devices, such as MEMS microspeakers, require protection due to their small size and fragility, and existing packaging solutions do not adequately enhance yield rate and sound pressure level (SPL) of acoustic waves.
Innovation Solution
A sound producing package structure comprising stacked sub-package structures with substrates and chips, where each sub-package has a membrane and cavity, connected via openings and gaps to form an ambient connection, enhancing the acoustic wave propagation and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If micro sound producing devices are protected using conventional packaging, then reliability is improved, but sound pressure level (SPL) is limited
Solution Approach 1:
The package structure is divided into multiple sub-packages (first sub-package and second sub-package), each containing its own chip with membrane and cavity. This segmentation allows independent acoustic wave generation in each sub-package while maintaining overall structural integrity and protection, thereby improving both reliability and sound pressure level.
Solution Approach 2:
The patent transitions from a single-plane packaging structure to a three-dimensional stacked configuration where sub-packages are vertically arranged. The first sub-package is positioned below the second sub-package, with gaps connecting their cavities to a common acoustic cavity. This vertical stacking enables multiple membranes to vibrate simultaneously in different spatial dimensions, significantly enhancing sound pressure level while maintaining device protection.
2Power
If multiple chips are stacked to increase SPL, then manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into independent stages: first sub-package manufacturing, second sub-package manufacturing, and final assembly. Each sub-package can be manufactured separately using standardized processes, and then stacked together. This segmentation reduces manufacturing complexity compared to creating a single complex multi-chip structure.
Solution Approach 2:
The patent employs a nested structure where the first sub-package is positioned within the overall package structure, and the second sub-package is stacked above it. The gaps between substrates create nested acoustic cavities that connect to a common acoustic space. This nesting approach simplifies the overall manufacturing by allowing modular assembly of standardized sub-packages.
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
The proposed structure increases the yield rate and reliability of the sound producing package and enhances the Sound Pressure Level (SPL) of the acoustic wave produced.
Implementation Method 1
a MEMS microspeaker may use a thin film piezoelectric material as actuator
Data Source
AI summary
A sound producing package structure includes a first sub-package structure and a second sub-package structure. The first sub-package structure includes a first substrate having a first opening and a first chip including a first membrane, wherein a first cavity is formed between the first membrane and the first substrate. The first sub-package structure and the second sub-package structure are stacked, and the second sub-package structure includes a second substrate and a second chip. The second substrate is connected to the first substrate and has a second opening. The second chip includes a second membrane, wherein a second cavity is formed between the second membrane and the second substrate. A gap, connected to the first opening and the second opening, is formed between the first substrate and the second substrate, such that an ambient of the sound producing package structure, the first cavity and the second cavity are connected.