Microchip Evaporative Cooling Channels to Prevent Dry-Out
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Solution Overview
Problem
Conventional evaporative cooling methods for microchips face challenges with high heat fluxes due to local dry-out at the wall and flow instabilities, which reduce heat transfer coefficients and require high flow rates.
Innovation Solution
A cooling element with a vaporization chamber and flow-modifying structures, such as pillars, that break up liquid slugs and vapor bubbles, combined with a vertically arranged condenser to drive gravity-driven flow, allowing for efficient heat transfer without a pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional evaporative cooling is used for high heat flux microchips, then cooling capability is provided, but local dry-out at the wall and flow instabilities occur which reduce heat transfer coefficients
Solution Approach 1:
The vaporization chamber is divided into multiple channels, and each channel is further segmented by protrusions that create smaller flow paths. This segmentation prevents large-scale dry-out by distributing the evaporative load across multiple smaller channels, ensuring more uniform liquid distribution and maintaining reliable heat transfer coefficients even at high heat fluxes.
Solution Approach 2:
Protrusions are strategically positioned within the channels to create localized flow modification zones. These protrusions generate specific flow patterns (such as liquid slugs and vapor bubbles) in localized regions, enhancing heat transfer in critical areas while preventing dry-out at the wall through controlled local fluid dynamics.
2Reliability
If high flow rates are used to prevent dry-out and maintain heat transfer, then cooling reliability improves, but the system complexity and energy consumption increase
Solution Approach 1:
The cooling system utilizes the heat from the microchip itself to drive the circulation of cooling liquid. The heated liquid becomes less dense and rises naturally, creating a convection current that continuously replenishes the liquid in the vaporization chamber without requiring external pumping. This self-service mechanism maintains reliable cooling effectiveness while eliminating pump power consumption.
Solution Approach 2:
The mechanical pump system is replaced with a natural convection system driven by density differences in the cooling liquid. Instead of using mechanical force to circulate the liquid, the system relies on thermal buoyancy forces created by the temperature difference between the heated liquid near the microchip and the cooler liquid in the condensation chamber, thereby eliminating mechanical complexity and energy consumption.
3Productivity
If a pump is added to maintain high flow rates for evaporative cooling, then heat dissipation performance improves, but device complexity increases
Solution Approach 1:
The system uses the heat generated by the microchip to drive the circulation of cooling liquid through natural convection. The heated liquid rises and flows to the condensation chamber, while cooler liquid sinks and flows back to the vaporization chamber, creating a continuous circulation loop without requiring any mechanical pumping components. This maintains high heat dissipation performance while keeping the system simple.
Solution Approach 2:
The pump component is completely extracted from the system. Instead of adding a pump to maintain high flow rates, the design relies on the natural convection currents generated by the temperature difference between the vaporization and condensation chambers to achieve the necessary liquid circulation for effective heat dissipation.
4Ease of manufacture
If conventional channel cooling is used, then manufacturing is simple, but cooling power is limited to maximum 0.18 W/cm²
Solution Approach 1:
The vaporization chamber is segmented into multiple channels with protrusions creating even smaller flow paths within each channel. This segmentation dramatically increases the total surface area available for heat transfer between the cooling liquid and the microchip, enabling cooling power densities far exceeding the conventional limit of 0.18 W/cm² while maintaining compatibility with standard semiconductor manufacturing processes.
Solution Approach 2:
The cooling approach transitions from simple planar channel cooling to a three-dimensional structure with protrusions extending into the channels. This adds a vertical dimension to the heat transfer surface, creating multiple levels of cooling contact area within the same footprint, thereby dramatically increasing cooling power density without complicating the manufacturing process.
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 configuration achieves high heat dissipation rates, prevents explosive bubble growth, and maintains low pressure drop, enabling efficient cooling of microchips with high heat fluxes while maintaining low flow rates.
Implementation Method 1
heat is exchanged from said integrated circuit to said cooling liquid thereby at least partially vaporizing said cooling liquid into vapor
Implementation Method 2
heat is exchanged from said integrated circuit to said cooling liquid
Implementation Method 3
vapor flows up through said first connection to the condenser and is condensed to cooling liquid in the condenser by heat exchange against ambient air
Implementation Method 4
only cooling liquid flows down from said one-way valve through said second connection by gravity flow
Data Source
Figure 1~2C
Figure 3~5
Figure 6A~6C
AI summary
The invention pertains to a method of cooling a microchip, using vaporization of a cooling liquid in a vaporization chamber of a cooling element wherein the vaporization chamber comprises channels and a plurality of flow- modifying structures.