Power Amplifier Module Heat Spreader With Peripheral Ground Connections

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Solution Overview

Problem

Conventional power amplifier modules face challenges in optimizing size reduction, thermal dissipation, and performance for current and emerging wireless communication systems, particularly in efficiently conveying RF signals and managing heat generated by power transistors.

Innovation Solution

The solution involves a power amplifier module design that incorporates a power transistor die and a heat spreader, where the power transistor die is thermally and electrically coupled to the heat spreader, which in turn is connected to a module substrate, enabling effective heat dissipation and signal transmission through conductive pillars and solder balls, while maintaining electrical connectivity to system ground.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the power transistor die is directly connected to the ground/thermal dissipation structure through the bottom-side conductive ground layer, then electrical connectivity is achieved, but thermal dissipation efficiency is insufficient

Engineering Contradiction:

Improvethermal dissipation efficiencyVSAvoidconnection structure complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent introduces a heat spreader as an intermediary component between the power transistor die and the module substrate. The heat spreader has a thermal contact surface that contacts the ground surface of the power transistor die, and an outer thermal contact surface that contacts the heat dissipation structure. This intermediary heat spreader improves thermal dissipation efficiency by providing a dedicated thermal conduction path while maintaining electrical connectivity through integrated ground contact structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If conventional direct connection methods are used between power transistor die and module substrate, then manufacturing is simplified, but thermal dissipation and electrical connectivity are insufficient

Engineering Contradiction:

Improveheat dissipation capabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent merges multiple functions into the heat spreader component: thermal conduction (via the thermal contact surface), electrical grounding (via ground contact structures), and mechanical support. The heat spreader combines thermal management and electrical connectivity functions in a single integrated component, improving both heat dissipation capability and electrical performance while maintaining manufacturing feasibility through standardized assembly processes.

Inventive Principle:

Principle #5Merging (Combining)

3Area of stationary object

If module size is reduced for compactness, then integration is improved, but thermal dissipation capacity is reduced

Engineering Contradiction:

Improvemodule sizeVSAvoidthermal dissipation capacity

Core Design Contradiction:

Area of stationary objectVSTemperature

Solution Approach 1:

The patent applies local quality by concentrating thermal management resources at the heat-generating region. The heat spreader is positioned directly under the power transistor die, creating a localized high-performance thermal conduction path. The ground contact structures are strategically placed at peripheral regions of the heat spreader, optimizing the thermal gradient and enabling efficient heat dissipation from the compact power transistor die without requiring the entire module to be large.

Inventive Principle:

Principle #3Local quality

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 design enhances thermal dissipation and electrical connectivity, improving the performance and efficiency of power amplifier modules by effectively managing heat and signal transmission, thereby optimizing module size and performance for various applications.

Implementation Method 1

the power transistor die is thermally and electrically coupled to the heat spreader, which in turn is connected to a module substrate, enabling effective heat dissipation

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

conveying RF signals between the module substrate and the power transistor die, electrical connections are made using bondwires

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11990384B2Amplifier modules with power transistor die and peripheral ground connections

Publication Date: 2024.05.21 NXP USA INC

AI summary

A power amplifier module includes a module substrate, a power transistor die, and a heat spreader. The module substrate has first, second, and third module pads exposed at a mounting surface. The power transistor die has an input/output surface that faces the mounting surface, an opposed ground surface, an input pad electrically coupled to the first module pad, an output pad electrically coupled to the second module pad, and an integrated power transistor. In an embodiment, the power transistor is a field effect transistor with a gate terminal coupled to the input pad, a drain terminal coupled to the output pad, and a source terminal coupled to the ground surface. The heat spreader has a thermal contact surface that is physically and electrically coupled to the ground surface of the power transistor die. An electrical ground contact structure is connected between the thermal contact surface and the third module pad.