BAW Filter Buried Connection Layer for Smaller High-Frequency Packages
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Solution Overview
Problem
Existing bulk acoustic wave (BAW) filters operate at high frequencies, making it difficult to reduce the size of their packages.
Innovation Solution
Incorporating a buried connection metal layer underneath the resonator in the BAW device package, which allows for a reduction in package size and enhances thermal dissipation and reduces parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional BAW filter structure is used, then high frequency operation is achieved, but package size reduction becomes difficult
Solution Approach 1:
The patent introduces a buried connection metal layer beneath the resonator structure, utilizing the vertical dimension (depth) to provide electrical connections. This allows the package footprint to be reduced by moving connection points from the horizontal plane to the vertical plane, effectively resolving the contradiction between maintaining high frequency operation and reducing package size.
Solution Approach 2:
The connection metal layer is nested within the package structure beneath the resonator, with cap substrate vias extending through the cap substrate to connect to the buried metal layer. This nested arrangement allows multiple functional elements (resonator, connection layer, vias) to occupy overlapping spatial regions, reducing the overall package footprint while maintaining high frequency performance.
2Area of stationary object
If the package size is reduced, then integration density improves, but thermal dissipation becomes more difficult
Solution Approach 1:
The buried connection metal layer serves as a thermal intermediary, conducting heat away from the resonator through the cap substrate vias to external heat sinks. This intermediary thermal path enables effective heat dissipation in the compact package structure by providing dedicated thermal conduction channels that do not occupy additional footprint area.
3Area of stationary object
If connection points are moved to the periphery, then package size is reduced, but parasitic capacitance increases
Solution Approach 1:
The patent creates different local qualities within the package structure: the buried connection metal layer provides low-capacitance connections beneath the resonator, while the cap substrate vias provide localized connection points. This localized connection approach minimizes parasitic capacitance by reducing the area of overlapping conductive surfaces compared to peripheral connections, while still achieving compact packaging.
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 solution achieves a 15-20% reduction in die size, improved thermal dissipation, and minimized parasitic capacitance, while maintaining optimal thermal paths and ground plane dimensions.
Implementation Method 1
improved thermal dissipation
Implementation Method 2
An acoustic wave device is disposed over at least a portion of the metal layer
Data Source
AI summary
A packaged acoustic wave component has a device substrate and a metal layer disposed over the device substrate. An acoustic wave device is disposed over at least a portion of the metal layer so that the metal layer is interposed between the device substrate and at least a portion of the acoustic wave device. A cap substrate is spaced above the device substrate, and peripheral wall that is attached to and extends between the device substrate and the cap substrate, the peripheral wall surrounding the acoustic wave device. One or more vias extend through the device substrate and are disposed under the metal layer.