Compact Rigid-Flex Packaging for Multiple MEMS Speakers
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Solution Overview
Problem
MEMS-based speakers face challenges in packaging due to size constraints and spatial limitations, which affect audio volume and quality, especially in compact form-factor devices like mobile phones and earbuds, as increasing the number of speakers to enhance audio volume increases overall package size.
Innovation Solution
A package design featuring two or more MEMS speakers on a substrate with a rigid-flex substrate configuration, including a spacer for a front acoustic chamber and efficient electrical connections, allowing for compact packaging without proportional size increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple MEMS speakers are packaged to increase audio volume, then the audio output capability is improved, but the package size increases proportionally
Solution Approach 1:
The patent implements nesting by placing one speaker die directly on top of another speaker die within the same package footprint. The first speaker die is mounted on a substrate, and the second speaker die is mounted on the first speaker die, creating a vertical stacked configuration. This nested arrangement allows multiple speakers to occupy the same horizontal space, thereby increasing audio output capability without proportionally increasing the package area.
Solution Approach 2:
The patent transitions from a two-dimensional horizontal arrangement of speakers to a three-dimensional vertical arrangement. By stacking speaker dies vertically along the z-axis rather than arranging them side-by-side in the x-y plane, the design exploits the third dimension to pack more speakers into a compact footprint, effectively decoupling audio output capability from package area.
2Volume of stationary object
If the package size is reduced to meet form factor constraints, then the device compactness is improved, but the audio volume and quality deteriorate
Solution Approach 1:
By nesting speaker dies vertically, the patent achieves high audio output capability within a compact horizontal footprint. The stacked configuration allows the package to maintain small area while accommodating multiple speakers that collectively provide sufficient audio volume and quality.
Solution Approach 2:
The vertical stacking approach enables the package to utilize the z-dimension for speaker arrangement, allowing compact x-y footprint while maintaining adequate speaker count for required audio performance. This dimensional transition resolves the contradiction between small package size and adequate audio output.
3Ease of manufacture
If conventional packaging methods are used for multiple speakers, then the manufacturing process is simple, but the acoustic isolation between speakers is insufficient leading to interference
Solution Approach 1:
The patent employs asymmetric acoustic isolation structures including a first acoustic isolation layer positioned between the first and second speaker dies, and a second acoustic isolation layer positioned between the second speaker die and the substrate. This asymmetric multi-layer isolation approach provides effective acoustic separation while maintaining manufacturing simplicity through sequential layer deposition.
Solution Approach 2:
The patent introduces acoustic isolation layers as intermediary structures between the speaker dies to prevent direct acoustic coupling. These isolation layers act as mediators that block harmful acoustic interference while allowing the speakers to operate in close proximity, thereby enabling compact packaging without sacrificing acoustic performance.
4Volume of stationary object
If speaker dies are placed in direct contact to save space, then the package density is improved, but the risk of damage during installation and handling increases
Solution Approach 1:
The patent implements beforehand cushioning by placing the first acoustic isolation layer between the first and second speaker dies, and the second acoustic isolation layer between the second speaker die and the substrate. These isolation layers serve as protective cushioning elements that prevent direct contact and potential damage during installation and handling, while still allowing compact vertical stacking.
Solution Approach 2:
The acoustic isolation layers function as intermediary protective elements between speaker dies, preventing direct mechanical contact that could cause damage. These intermediaries maintain the compact vertical arrangement while providing necessary mechanical protection, thereby resolving the contradiction between package density and speaker die reliability.
Data Source
AI summary
A package for multiple MEMS-based speakers in a compact form factor is provided. One package includes: a first rigid section defining a first vent aperture; a second rigid section defining a second vent aperture; a first speaker die attached to the first rigid section and covering the first vent aperture; a second speaker die attached to the second rigid section and covering the second vent aperture; a first flexible section attached between and providing electrical continuity between the first rigid section and the second rigid section; and a spacer defining an acoustic port, where the first rigid section is attached to a first side of the spacer, and the second rigid section is attached to a second side of the spacer, where the first speaker die faces the second speaker die.