Power Amplifier Module Thermal Management via Rear Surface Dissipation
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Solution Overview
Problem
In power amplifier modules, the heat dissipation of a SAW duplexer is hindered by its cavity when mounted face-down, making it difficult to dissipate heat through thermal vias, which is a challenge in compact radio communication devices.
Innovation Solution
A power amplifier module configuration that includes a substrate with thermal vias, a power amplifier mounted face-down with electrodes connected to the substrate, a SAW duplexer with a conductive unit on its surface electrically connected to a conductive shield, and an insulating resin covering both components, enhancing heat dissipation through the conductive shield and thermal vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the SAW duplexer is mounted face-down to make the module compact, then the module size is reduced, but heat dissipation capability deteriorates because the cavity prevents heat from reaching thermal vias
Solution Approach 1:
The patent introduces a new heat dissipation dimension by adding a heat dissipation unit on the rear surface of the package substrate. Instead of relying solely on thermal vias through the substrate thickness, heat can now be dissipated through a third dimension (the rear surface), bypassing the cavity obstruction problem caused by face-down mounting.
Solution Approach 2:
The heat dissipation function is segmented into multiple paths: thermal vias for the power amplifier and a separate heat dissipation unit on the rear surface for the SAW duplexer. This segmentation allows each component to have its own optimized heat dissipation route, overcoming the limitation that a single thermal via approach cannot serve both face-down mounted components effectively.
2Temperature
If thermal vias are used to dissipate heat from face-down mounted components, then heat dissipation is improved, but the cavity in the SAW duplexer blocks the heat path from the interdigital electrode unit to the package substrate
Solution Approach 1:
The patent introduces an intermediary heat dissipation unit on the rear surface of the package substrate. This intermediary structure receives heat from the SAW duplexer through the package substrate and dissipates it externally, acting as a mediator that bridges the gap between the blocked thermal via path and the external environment.
Solution Approach 2:
The heat dissipation function for the SAW duplexer is extracted from the internal thermal via path and relocated to the rear surface of the package substrate. This extraction removes the conflict between the cavity structure and the thermal via, allowing the SAW duplexer to dissipate heat through a separate, unobstructed path.
3Volume of moving object
If both power amplifier and SAW duplexer are mounted face-down for compactness, then module compactness is improved, but heat dissipation from both components becomes difficult due to the cavity obstruction
Solution Approach 1:
The heat dissipation system is segmented into two independent pathways: one through thermal vias for the power amplifier and another through the rear surface heat dissipation unit for the SAW duplexer. This segmentation ensures that the cavity in the SAW duplexer does not compromise the heat dissipation reliability of either component, maintaining system reliability while preserving compactness.
Solution Approach 2:
The patent adds a rear surface dimension for heat dissipation, creating a three-dimensional heat dissipation architecture. This allows both face-down mounted components to dissipate heat effectively: the power amplifier through substrate thermal vias and the SAW duplexer through the rear surface heat dissipation unit, thereby maintaining reliability without sacrificing compactness.
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 the heat dissipation capability of the power amplifier module by allowing heat from both the power amplifier and SAW duplexer to be effectively dissipated, stabilizing the operation and reducing the risk of heat-related issues in compact radio communication devices.
Implementation Method 1
an emitter electrode of a power amplifier mounted face-down on a front surface of a package substrate is connected to a thermal via formed in the package substrate, resulting in heat of the power amplifier being dissipated from a rear surface of the package substrate
Implementation Method 2
a conductive shield that covers a surface of the insulating resin, and a first conductive unit defined on the second surface of the surface acoustic wave duplexer and electrically connected to the conductive shield
Data Source
AI summary
A power amplifier module includes a substrate, a power amplifier having a first surface on which an electrode is defined and a second surface opposite the first surface, the first surface faces a principal surface of the substrate, a surface acoustic wave duplexer having a first surface on which an electrode is defined and a second surface opposite the first surface, the first surface faces the principal surface of the substrate, a heat dissipation unit defined on another principal surface of the substrate, a heat dissipation path that connects a connecting portion between the power amplifier and the principal surface to the heat dissipation unit, an insulating resin that covers the power amplifier and the surface acoustic wave duplexer, a conductive shield that covers the insulating resin, and a first conductive unit defined on the second surface of the surface acoustic wave duplexer and electrically connected to the conductive shield.