Two-Phase Thermal Ground Plane With Capillary Wick for Thin Devices
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Solution Overview
Problem
Existing cooling systems for semiconductor devices face challenges in efficiently managing heat in confined, thin-planar configurations, particularly in portable devices where size, power consumption, and battery life are critical, and traditional heat pipes are inefficient and bulky.
Innovation Solution
The development of two-phase cooling devices featuring microfabricated metal substrates, such as titanium, with etched microstructures forming a wicking structure and a vapor cavity, utilizing capillary forces to efficiently transfer thermal energy across regions, including an evaporator, adiabatic, and condenser regions, while minimizing viscous losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional heat pipes are used for cooling semiconductor devices, then heat transfer function is provided, but the device becomes bulky and inefficient in thin-planar configurations
Solution Approach 1:
The patent employs two-phase heat transfer utilizing phase transitions of a working fluid between liquid and vapor states. The fluid evaporates at the heat source absorbing latent heat, then condenses at the heat sink releasing heat, enabling highly efficient thermal management in a thin-planar configuration without requiring bulky traditional heat pipe structures
Solution Approach 2:
The patent utilizes a porous wicking structure made of hydrophilic material to transport the liquid working fluid from the condenser region back to the evaporator region through capillary forces. This porous medium enables effective fluid transport in the thin-planar geometry while maintaining high heat transfer efficiency
2Length of moving object
If the thermal ground plane is made thinner to fit portable devices, then device compactness is improved, but heat transfer capability may be reduced
Solution Approach 1:
By utilizing phase transitions of the working fluid, the patent achieves high heat transfer rates in a thin-planar configuration. The latent heat absorption during evaporation and release during condensation provide intense heat transfer capability that compensates for the reduced thickness, enabling effective cooling in portable devices with strict space constraints
3Stress or pressure
If capillary forces are increased in the wicking structure to support large pressure differences, then fluid transport capability is improved, but viscous losses increase
Solution Approach 1:
The patent employs a porous wicking structure with optimized pore size distribution and hydrophilic properties to generate sufficient capillary forces for supporting large pressure differences between evaporator and condenser regions. The porous structure's capillary pressure is tuned to match the operating pressure differential while minimizing flow resistance and viscous losses through appropriate pore geometry and material selection
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 solution enables higher heat transfer rates, thinner thermal ground planes, and improved mechanical strength, reducing the risk of dryout and enhancing the reliability and battery life of portable devices by effectively managing heat in compact designs.
Implementation Method 1
a fluid may be contained within the wicking structure and vapor cavity for transporting thermal energy from one region of the thermal ground plane to another region of the thermal ground plane, wherein the fluid may be driven by capillary forces within the wicking structure
Implementation Method 2
the working fluid adsorbs or rejects heat by changing phases between liquid and vapor
Data Source
AI summary
The present application discloses two-phase cooling devices that may include at least three substrates, a metal with a wicking structure, an intermediate substrate, and a backplane. A fluid may be contained within the wicking structure and vapor cavity for transporting thermal energy from one region of the thermal ground plane to another region of the thermal ground plane, wherein the fluid may be driven by capillary forces within the wicking structure. The titanium thermal ground plane may be adapted for use in a mobile device, such as a portable device or smartphone, where it may offer compelling performance advantages.