Topside Cooling Interface for RF Power Amplifier Module Heat Dissipation

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Solution Overview

Problem

Traditional power amplifier modules (PAMs) face limitations in heat dissipation due to the use of bottomside heat dissipation structures, which are costly and complex, and often fail to efficiently manage excess heat generated by RF power dies, especially at higher frequencies.

Innovation Solution

The implementation of topside cooling interfaces, which provide a direct and efficient heat extraction path from the RF power die to an external heatsink, bypassing lower thermal conductivity materials in the module substrate, and allowing for enhanced heat dissipation through a thermally conductive pathway.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If bottomside heat dissipation structures are used, then heat dissipation is provided, but fabrication costs increase and routing schemes become complex

Engineering Contradiction:

Improveheat dissipationVSAvoidrouting schemes

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent inverts the traditional bottomside heat dissipation approach by implementing a topside heat dissipation structure. The thermal via is formed through the module substrate from the topside surface, allowing the heat dissipation pathway to be reversed and eliminating complex routing schemes while reducing fabrication costs.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts the heat dissipation function from the complex bottomside routing structure and consolidates it into a single thermal via pathway. This extraction simplifies the overall routing scheme by removing unnecessary complex interconnections while maintaining effective heat dissipation.

Inventive Principle:

Principle #2Taking out (Extraction)

2Temperature

If bottomside heat dissipation structures are used, then heat dissipation is provided, but fabrication costs increase

Engineering Contradiction:

Improveheat dissipationVSAvoidfabrication costs

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent reverses the traditional heat dissipation pathway from bottomside to topside, forming the thermal via through the module substrate from the topside surface. This inversion simplifies the manufacturing process and reduces fabrication costs by eliminating complex routing structures while maintaining effective heat dissipation.

Inventive Principle:

Principle #13The other way round (Inversion)

3Power

If RF power dies are operated at higher frequencies, then power amplification performance is improved, but excess heat generation increases

Engineering Contradiction:

Improvepower amplification performanceVSAvoidexcess heat generation

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The patent introduces a thermal via as an intermediary heat conduction pathway between the RF power die and the heat sink. This thermal via acts as a mediator that efficiently transfers excess heat generated during high-frequency operation, enabling the RF power die to maintain high performance while effectively managing thermal accumulation.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Temperature

If traditional bottomside heat dissipation is used, then heat dissipation is achieved, but thermal performance is limited

Engineering Contradiction:

Improveheat dissipationVSAvoidthermal performance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent inverts the heat dissipation pathway from bottomside to topside, creating a direct thermal via pathway that improves thermal performance. This inversion allows for more efficient heat extraction from the RF power die, enhancing overall thermal management reliability while maintaining effective heat dissipation.

Inventive Principle:

Principle #13The other way round (Inversion)

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 approach significantly improves thermal performance by allowing for efficient heat dissipation from RF power dies, reducing fabrication costs, and simplifying routing schemes, while maintaining electrical performance at higher frequencies.

Implementation Method 1

a thermal via extending through the module substrate from a topside surface of the module substrate to a bottomside surface of the module substrate, the thermal via providing the heat extraction path

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11990872B2Power amplifier modules including topside cooling interfaces and methods for the fabrication thereof

Publication Date: 2024.05.21 NXP USA INC

AI summary

Power amplifier modules (PAMs) having topside cooling interfaces are disclosed, as are methods for fabricating such PAMs. In embodiments, the method includes attaching the RF power die to a die support-surface of a module substrate. The RF power die is attached to the module substrate in an inverted orientation such that a frontside of the RF power die faces the module substrate. When attaching the RF power die to the module substrate, a frontside input/output interface of the RF power die is electrically coupled to corresponding substrate interconnect features of the module substrate. The method further includes providing a primary heat extraction path extending from the transistor channel of the RF power die to a topside cooling interface of the PAM in a direction opposite the module substrate.