Variable-Thickness Vapor Core for Thin Thermal Ground Planes
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Solution Overview
Problem
Conventional thermal ground planes face challenges in efficiently managing heat transfer due to fixed vapor core thickness, which affects thermal performance, especially in thin designs used in mobile devices where every micron counts, leading to suboptimal vapor transport and increased thermal resistance.
Innovation Solution
A thermal ground plane with a variable thickness vapor core, where the gap between casings can adjust to accommodate void spaces and circuit element shapes, utilizing spacers and wicking structures to enhance vapor transport, and potentially include elastic materials or additional wicking layers to optimize heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the vapor core thickness is reduced to achieve thinner thermal ground plane designs for mobile devices, then the device thickness is reduced, but the vapor transport efficiency deteriorates and thermal resistance increases
Solution Approach 1:
The vapor core is segmented into multiple sections with different thicknesses along its length. The thickness varies from a first thickness at the evaporator end to a second thickness at the condenser end, allowing each section to be optimized for its specific function while maintaining overall thinness of the thermal ground plane
Solution Approach 2:
Different sections of the vapor core are given different local qualities through varying thickness. The evaporator end has a thinner vapor core section to reduce overall thickness, while the condenser end has a thicker vapor core section to maintain vapor transport efficiency and reduce thermal resistance
2Reliability
If the vapor core thickness is increased to improve vapor transport efficiency, then the vapor transport efficiency is improved, but the thermal ground plane thickness increases
Solution Approach 1:
The vapor core is divided into multiple sections with varying thicknesses, allowing the thickness to be increased only where needed for vapor transport (at the condenser end) while keeping other sections (evaporator end) thinner to maintain overall compactness
Solution Approach 2:
The vapor core thickness is locally optimized: thinner at the evaporator end to reduce overall thickness, and thicker at the condenser end to enhance vapor transport efficiency, creating a non-uniform thickness distribution that balances both requirements
3Ease of manufacture
If a fixed thickness vapor core is used, then the manufacturing process is simplified, but the thermal performance is suboptimal for varying heat loads and device contours
Solution Approach 1:
The vapor core transitions from a static fixed-thickness design to a dynamic variable-thickness design where the thickness changes along the length of the vapor core, allowing the structure to adapt to varying heat loads and device contours while maintaining manufacturability through techniques like variable thickness spacer placement
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 significantly enhances thermal performance by varying the vapor core thickness to match device contours, improving vapor transport and reducing thermal resistance, potentially achieving thermal conductivity 3-50 times higher than copper, depending on configuration.
Implementation Method 1
a wicking layer disposed between the first casing and the second casing
Implementation Method 2
an evaporator region disposed at least partially on at least one of the first casing and the second casing
Implementation Method 3
a condenser region disposed at least partially on at least one of the first casing and the second casing
Implementation Method 4
a vapor core defined at least partially by a gap between the first casing and the second casing
Data Source
AI summary
Some embodiments of the invention include a thermal ground plane with a variable thickness vapor core. For example, a thermal ground plan may include a first casing and a second casing where the second casing and the first casing configured to enclose a working fluid. The thermal ground plane may also include an evaporator region disposed at least partially on at least one of the first casing and the second casing; a condenser region disposed at least partially on at least one of the first casing and the second casing; and a wicking layer disposed between the first casing and the second casing a vapor core defined at least partially by a gap between the first casing and the second casing. The thickness of the gap can vary across the first casing and the second casing.