RF Module Acoustic Filter Layout for Better Heat Dissipation
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Solution Overview
Problem
In existing radio-frequency modules, particularly those with multiband support, the heat dissipation of acoustic wave filters is insufficient, leading to deteriorated filter characteristics due to temperature changes.
Innovation Solution
The radio-frequency module is designed with a module substrate having facing main surfaces, where the acoustic wave filter's bottom surface is closer to one main surface and connected to a metal electrode on the other, allowing heat dissipation through a direct path to an external substrate, bypassing the substrate's planar wiring pattern with high thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the acoustic wave filter is disposed on the main surface with external connection terminals, then the filter can be easily connected to external circuits, but heat dissipation becomes insufficient leading to temperature rise and filter characteristic deterioration
Solution Approach 1:
The patent transitions from planar heat dissipation within the substrate to three-dimensional heat dissipation by extending the thermal conduction path vertically. The acoustic wave filter is positioned closer to one main surface while a metal electrode on the opposite surface provides a direct thermal conduction path through the substrate thickness, utilizing the third dimension (z-axis) to improve heat dissipation efficiency without compromising electrical connection ease on the surface.
2Device complexity
If heat dissipation relies on the planar wiring pattern in the substrate, then the structure remains simple, but thermal resistance is high causing insufficient heat dissipation
Solution Approach 1:
The patent introduces a metal electrode as an intermediary thermal conduction element between the acoustic wave filter and the external environment. This metal electrode acts as a thermal mediator that bridges the heat flow path, providing a low thermal resistance connection that complements the existing substrate structure without requiring complete redesign of the planar wiring pattern.
3Temperature
If the acoustic wave filter is positioned closer to the main surface, then heat can be dissipated more directly, but the filter may be more exposed to external thermal interference
Solution Approach 1:
The patent employs asymmetric positioning of the acoustic wave filter relative to the substrate thickness, placing it closer to one main surface rather than at the center. This asymmetric configuration creates an uneven thermal path where the shorter distance to the metal electrode on the opposite surface provides preferential heat dissipation, while the substrate material still provides thermal isolation from external environmental interference on the other side.
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
This configuration improves heat dissipation of the acoustic wave filter, maintaining filter characteristics and reducing thermal stress, thereby enhancing the module's performance.
Implementation Method 1
heat dissipation through a direct path to an external substrate, bypassing the substrate's planar wiring pattern with high thermal resistance
Data Source
AI summary
A radio-frequency module includes a module substrate having main surfaces facing each other, a transmission filter that has a bottom surface and a top surface facing each other and passes a radio-frequency signal, and an external connection terminal disposed on the main surface. The bottom surface faces the main surface and is disposed closer to the main surface than the top surface. The radio-frequency module further includes a metal electrode joined to the top surface.