Thermal Extension Levels for RF Module Heat Dissipation

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Solution Overview

Problem

Existing thermal solutions for microelectronic modules, such as those containing RF semiconductor die, are inadequate in dissipating excess heat, leading to elevated local temperatures and performance degradation.

Innovation Solution

Incorporation of a thermal extension level with a heat spreader extension and substrate-embedded heat spreader, bonded via a thermally-conductive bond layer, to form a conductive thermal conduit that transfers heat from the module to a system substrate, enhancing convective heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If existing thermal solutions (bar vias or metal bodies) are implemented in the module substrate, then heat dissipation is enhanced to some extent, but thermal performance remains inadequate and hot spots still develop

Engineering Contradiction:
Improveheat dissipation capabilityVSAvoidthermal performance adequacy
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent extends the thermal management solution from the substrate interior to the exterior surface by adding a thermal extension level that protrudes from the backside of the substrate. This dimensional extension creates additional thermal pathways and increases the effective heat dissipation surface area, resolving the inadequacy of conventional embedded thermal structures.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The thermal management system is divided into distinct functional components: substrate-embedded heat spreader, thermally-conductive bond layer, and heat spreader extension. This segmentation allows each component to be optimized independently and assembled into a integrated thermal conduit system that overcomes the limitations of single-structure solutions.

Inventive Principle:
Principle #1Segmentation

2Temperature

If metal content within the module substrate is increased to enhance thermal performance, then heat dissipation is improved, but the substrate structure becomes more complex and manufacturing difficulty increases

Engineering Contradiction:
Improveheat dissipation capabilityVSAvoidsubstrate fabrication complexity
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The thermal management function is segmented from the substrate fabrication process. Instead of incorporating complex metal structures during substrate manufacturing, the patent uses a modular approach where pre-fabricated thermal components are assembled onto the substrate, simplifying the substrate fabrication process while achieving superior thermal performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A thermally-conductive bond layer serves as an intermediary between the substrate-embedded heat spreader and the heat spreader extension. This intermediary component facilitates thermal transfer between structures while allowing independent optimization of each component's manufacturing process, reducing overall system complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If conventional thermal structures are embedded within the substrate body, then some heat dissipation is achieved, but thermal gradients are not uniformly distributed and hot spots persist

Engineering Contradiction:
Improveheat dissipation capabilityVSAvoidthermal gradient uniformity
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

By extending the heat spreader structure from the substrate interior to the exterior surface, the patent creates additional thermal pathways in the vertical dimension. This extension distributes heat more effectively across multiple levels, reducing thermal gradients and eliminating hot spots that persist with conventional embedded structures.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The thermal management system employs a composite structure combining substrate-embedded heat spreader, thermally-conductive bond layer, and heat spreader extension made of thermally-conductive materials. This composite architecture provides superior thermal distribution compared to single-material solutions, achieving uniform thermal gradients across the module.

Inventive Principle:
Principle #40Composite materials

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 effectively increases thermal dissipation capabilities, allowing microelectronic devices to operate at higher power levels with minimal performance degradation by uniformly distributing thermal gradients and promoting both conductive and convective heat transfer.

Implementation Method 1

bonded via a thermally-conductive bond layer, to form a conductive thermal conduit that transfers heat

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

enhancing convective heat dissipation

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3588553B1Microelectronic modules including thermal extension levels and methods for the fabrication thereof
Publication Date: 2025.08.20 NXP USA INC
  • EP3588553B1 patent drawingFigure 1
  • EP3588553B1 patent drawingFigure 2
  • EP3588553B1 patent drawingFigure 3

AI summary

High thermal performance microelectronic modules containing thermal extension levels are provided, as are methods for fabricating such microelectronic modules. In various embodiments, the microelectronic module includes a module substrate having a substrate frontside and a substrate backside. At least one a microelectronic device, such as a semiconductor die bearing radio frequency circuity, is mounted to the substrate frontside. A substrate-embedded heat spreader, which is thermally coupled to the microelectronic device, is at least partially contained within the module substrate, and extends to the substrate backside. A thermal extension level is located adjacent the substrate backside and extends away from the substrate backside to terminate at a module mount plane. The thermal extension level contains a heat spreader extension, which is bonded to and in thermal communication with the substrate-embedded heat spreader.