Bi-Directional TEC in PoP Stacks for Dynamic Die Heat Transfer

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Solution Overview

Problem

Current package-on-package (PoP) devices with passive heat spreaders lack active control over heat dissipation, making them ineffective for managing thermal loads in multi-die configurations, particularly in mobile and wearable devices where intelligent thermal management is required.

Innovation Solution

A bi-directional thermal electric cooler (TEC) is integrated between two packages to dynamically dissipate heat back and forth, using a thermally conductive adhesive and interconnects to manage heat transfer between dies, allowing for real-time temperature regulation and optimal performance within thermal limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a passive heat spreader is used, then heat dissipation structure is simple, but active control of heat dissipation is lost and thermal management becomes ineffective for multi-die configurations

Engineering Contradiction:
Improveactive control of heat dissipationVSAvoidthermal management structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by implementing a bi-directional thermal electric cooler (TEC) that can dynamically change its heat dissipation direction based on real-time temperature conditions. The TEC is controlled to dissipate heat from either the first die or the second die depending on which die exceeds its maximum operating temperature, transforming the static passive heat spreader into a dynamic active thermal management system. This allows the system to adaptively respond to varying thermal loads in multi-die configurations.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If a heat spreader is used for single die, then heat dissipation is achieved, but it is not applicable for effective thermal management of devices with several dies

Engineering Contradiction:
Improveapplicability to multi-die configurationsVSAvoidthermal management effectiveness
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies the universality principle by designing a bi-directional TEC system that can serve multiple thermal management functions within a single device. The same TEC component can dissipate heat from either the first die or the second die, or both simultaneously at different times, making the thermal management system universally applicable to multi-die configurations. This multi-functional capability ensures reliable thermal management across various operating conditions and die combinations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Temperature

If passive heat dissipation is used, then device structure is simple, but dynamic heat flow control and real-time temperature regulation are not achieved

Engineering Contradiction:
Improvereal-time temperature regulationVSAvoidthermal control mechanism
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent applies the feedback principle by implementing temperature sensors that continuously monitor the temperature of each die and feed this information back to the control logic. The control system uses this feedback to determine when the first die or second die exceeds its maximum operating temperature and accordingly activates the bi-directional TEC to dissipate heat from the appropriate die. This closed-loop feedback mechanism enables precise real-time temperature regulation while maintaining reasonable system complexity.

Inventive Principle:
Principle #23Feedback

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 bi-directional TEC effectively manages thermal loads by dynamically transferring heat between dies, ensuring optimal performance and preventing overheating, thus addressing the limitations of passive heat spreaders in multi-die configurations.

Implementation Method 1

a bi-directional thermal electric cooler, TEC, located between the first die and the second substrate, the bi-directional TEC adapted to dynamically dissipate heat back and forth between the first package and the second package

Methodology Applied
Scientific EffectPeltier Effect: Peltier Effect

Implementation Method 2

using a thermally conductive adhesive and interconnects to manage heat transfer between dies

Methodology Applied
Scientific EffectThermal Conduction: Conduction (thermal)

Data Source

PatentEP3295481B1Package-on-package (POP) device comprising bi-directional thermal electric cooler
Publication Date: 2025.03.26 QUALCOMM INC
  • EP3295481B1 patent drawingFigure 1
  • EP3295481B1 patent drawingFigure 2
  • EP3295481B1 patent drawingFigure 3~4

AI summary

A package-on-package (PoP) device includes a first package, a second package, and a bi-directional thermal electric cooler (TEC). The first package includes a first substrate and a first die coupled to the first substrate. The second package is coupled to the first package. The second package includes a second substrate and a second die coupled to the second substrate. The TEC is located between the first die and the second substrate. The TEC is adapted to dynamically dissipate heat back and forth between the first package and the second package. The TEC is adapted to dissipate heat from the first die to the second die in a first time period. The TEC is further adapted to dissipate heat from the second die to the first die in a second time period. The TEC is adapted to dissipate heat from the first die to the second die through the second substrate.