Self-Shielded Acoustic Wave Package for Floating Capacitance Control
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Solution Overview
Problem
Existing bulk acoustic wave (BAW) filters face challenges in size reduction due to high frequency operation, leading to difficulties in packaging and increased floating capacitance with other electrical components.
Innovation Solution
A packaged acoustic wave component with a shield structure comprising a metal plate and peripheral metal wall that encloses and electrically shields the BAW resonator, reducing floating capacitance and allowing for smaller module sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a BAW device is operated at high frequency to achieve better filter performance, then the filter performance is improved, but the package size reduction becomes difficult
Solution Approach 1:
The shield structure is nested within the package cavity, with the metal plate positioned on the cap substrate and the peripheral metal wall extending down to enclose the BAW device. This nested arrangement provides effective electrical shielding without adding external package volume, allowing high-frequency operation with improved filter performance while maintaining compact package size.
2Reliability
If electrical shielding is added to prevent floating capacitance, then electrical performance is improved, but device complexity increases
Solution Approach 1:
The shield structure merges the metal plate and peripheral metal wall into a unified enclosure that integrates with the cap substrate and device substrate. This combined structure provides comprehensive electrical shielding against floating capacitance while avoiding the complexity of multiple separate shielding components, thus improving electrical performance without excessive device complexity.
3Productivity
If component placement is moved closer to reduce module size, then productivity is improved, but electrical interference increases
Solution Approach 1:
The shield structure is预先 installed within the package cavity before final component placement, creating a pre-established electrical barrier. This preliminary shielding action prevents floating capacitance and electrical interference from developing, enabling components to be placed closer together for higher productivity without suffering from increased electrical interference.
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 shield structure inhibits floating capacitance, improving filter performance and enabling closer component placement, resulting in a reduction in module size while maintaining effective electrical shielding.
Implementation Method 1
a shield structure including a metal plate disposed on a bottom surface of the cap substrate that faces the device substrate, the metal plate being spaced above the acoustic wave device, and a peripheral metal wall attached to the metal plate that extends to the device substrate. The shield structure encloses and electrically shields the acoustic wave device.
Data Source
AI summary
A method of manufacturing a packaged acoustic wave component includes forming or providing a cap substrate. The method also includes forming a metal shield plate on a surface of the cap substrate. The cap substrate is attached to a device substrate that has an acoustic wave device on a surface thereof such that the metal shield plate is spaced from and faces the acoustic wave device and so that a peripheral metal wall extends between the device substrate and the metal plate. The metal shield plate and peripheral metal wall enclose and electrically shield the acoustic wave device.