Vapor Chamber Wick Structure to Prevent Center Dry-Out
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Solution Overview
Problem
Existing vapor chambers experience reverse flow of working liquid, leading to dry-out at the center portion of the wick, which hinders effective heat transfer and can cause thermal runaway in electronic devices.
Innovation Solution
A vapor chamber design with a casing formed by two sheets bonded at their peripheries, containing a wick with protruding portions and a mesh, and a wall portion around the wick to control the liquid flow, preventing reverse flow and ensuring continuous circulation of the working liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional wick structure is used in the vapor chamber, then the device complexity is reduced, but reverse flow of working liquid occurs causing dry-out at the center portion of the wick
Solution Approach 1:
The wick is divided into multiple functional regions: a center portion with higher porosity for liquid supply, and an outer peripheral portion with lower porosity to prevent reverse flow. This segmentation allows each region to perform its specific function optimally, preventing dry-out while maintaining manageable device complexity.
Solution Approach 2:
Different porosity characteristics are applied to different locations of the wick. The center portion has higher porosity to facilitate liquid supply to the heating surface, while the outer peripheral portion has lower porosity to prevent reverse flow. This local differentiation of properties solves the dry-out problem without requiring complex overall structure.
2Reliability
If the wick porosity is increased to improve liquid supply, then the heat transfer ability is improved, but reverse flow of working liquid occurs
Solution Approach 1:
The wick exhibits spatially varying porosity: higher porosity at the center for effective liquid supply and heat transfer, and lower porosity at the outer periphery to prevent reverse flow. This local quality differentiation allows the system to achieve both improved heat transfer and prevention of harmful reverse flow.
Solution Approach 2:
The porosity gradient structure converts the potential harm of reverse flow into a beneficial flow control mechanism. The lower porosity outer region acts as a flow barrier that redirects liquid movement, ensuring unidirectional flow from the outer periphery toward the center, thus eliminating reverse flow while maintaining heat transfer effectiveness.
3Productivity
If a uniform wick structure is used, then the manufacturing process is simplified, but the working liquid circulation is disrupted
Solution Approach 1:
The porosity parameter of the wick is varied spatially to optimize liquid circulation. By changing the porosity from high at the center to low at the outer periphery, the system achieves efficient unidirectional liquid flow. This parameter change can be implemented through controlled manufacturing processes, balancing productivity improvement with manufacturing feasibility.
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
Prevents dry-out by ensuring continuous supply of working liquid to the center portion of the wick, enhancing heat transfer and maintaining effective cooling of heat sources.
Implementation Method 1
the mesh comprises a material with a high capillary action
Implementation Method 2
the working liquid sealed in the casing is, when the inside of the casing is viewed from an upper surface of the casing, vaporized at a center portion of the wick, and liquefied at end portions (outer peripheral portions) of the wick
Implementation Method 3
a vapor chamber which is a planar heat pipe
Data Source
AI summary
To provide a vapor chamber having excellent function of circulating a working liquid from an end portion to a center portion of a wick and enabling the prevention of the occurrence of dry-out. A vapor chamber includes a casing formed of a first sheet and a second sheet which face each other and whose outer peripheries are bonded to each other; a working liquid sealed in the casing; and a wick disposed on an inner wall surface of the first sheet or the second sheet. A wall portion is disposed around the wick as viewed in a top plan view of an inside of the casing.