SAW Filter Assembly With Conductive Sheet for Heat Dissipation
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Solution Overview
Problem
Surface acoustic wave filters face challenges in managing heat generated by high-power radio frequency signals, leading to thermal issues that affect their durability and performance.
Innovation Solution
Incorporating a thermally conductive layer with high thermal conductivity, such as aluminum nitride, which is thinner than the piezoelectric layer and in physical contact with it, to effectively dissipate heat and improve thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermally conductive layer is added to dissipate heat, then thermal performance is improved, but device complexity increases
Solution Approach 1:
The patent changes the thermal conductivity parameter of the layer structure by selecting materials with high thermal conductivity (such as aluminum nitride with thermal conductivity of 150-200 W/mK) for the thermally conductive layer, while controlling the layer thickness parameter (6.3-25 micrometers) to optimize the balance between heat dissipation performance and device complexity
Solution Approach 2:
The patent employs a composite layer structure consisting of a piezoelectric layer (lithium niobate or lithium tantalate) and a thermally conductive layer (aluminum nitride, silicon nitride, or diamond-like carbon). This composite structure combines the piezoelectric properties needed for SAW filter operation with the thermal conductivity needed for heat dissipation, resolving the contradiction between functional performance and thermal management
2Ease of manufacture
If the thermally conductive layer is made thinner to reduce complexity, then manufacturing is simplified, but heat dissipation effectiveness decreases
Solution Approach 1:
The patent optimizes the thickness parameter of the thermally conductive layer to a specific range (6.3-25 micrometers, preferably 10-20 micrometers). This parameter selection achieves an optimal balance: thin enough to maintain device compactness and simplify manufacturing processes, yet thick enough to provide effective thermal conduction path from the IDT electrode to the substrate, dissipating heat generated during high-power RF operation
3Productivity
If high-power signals are filtered to improve performance, then more heat is generated, but filtering capability is improved
Solution Approach 1:
The patent converts the harmful heat generated by high-power signal filtering into a manageable thermal conduction problem. By incorporating a thermally conductive layer with high thermal conductivity materials (aluminum nitride, silicon nitride, or diamond-like carbon), the heat generated during high-power RF signal filtering is efficiently conducted away from the IDT electrode through the piezoelectric layer to the substrate, allowing the filter to maintain high filtering capability while managing the thermal load
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 significantly reduces maximum chip temperature, enhancing the power durability and thermal performance of surface acoustic wave filters, allowing for efficient filtering of high-power radio frequency signals while minimizing material usage and manufacturing complexities.
Implementation Method 1
a thermally conductive layer configured to dissipate heat of the surface acoustic wave device. The thermally conductive layer can have a thermal conductivity that is at least 5 times the thermal conductivity of the piezoelectric layer
Implementation Method 2
a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer
Data Source
AI summary
Aspects of this disclosure relate to a surface acoustic wave assembly that includes a first surface acoustic wave filter, a second surface acoustic wave filter, and a thermally conductive sheet configured to dissipate heat from the first surface acoustic wave filter in an area corresponding to the second surface acoustic wave filter. The thermally conductive sheet can be thinner than a piezoelectric layer of the first surface acoustic wave filter. Related radio frequency modules and methods are disclosed.