Boiling Enhancement Coating for Direct-to-Chip Immersion Cooling
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Solution Overview
Problem
As feature sizes decrease in integrated circuits, the heat generated by individual chips increases, requiring more efficient heat dissipation methods than air cooling, with two-phase immersion cooling being employed but needing enhancement to improve thermal performance.
Innovation Solution
A boiling enhancement coating (BEC) is applied directly to the chip or package, forming a roughened surface that enhances nucleate boiling of the coolant liquid in two-phase immersion-cooling systems, using various methods such as spraying, electro-static deposition, or soldering, to increase heat transfer coefficients and accelerate boiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If air cooling is used for chips, then the cooling system is simple, but it cannot dissipate the increased heat generated by smaller feature sizes
Solution Approach 1:
The patent employs two-phase immersion cooling where the coolant liquid undergoes phase transition from liquid to vapor during boiling, absorbing latent heat from the chip. This phase change mechanism enables highly efficient heat dissipation that far exceeds conventional air cooling, allowing the system to manage increased heat generation from smaller feature sizes while maintaining relatively simple system architecture.
2Temperature
If two-phase immersion cooling is used, then heat dissipation capability is improved, but boiling efficiency needs enhancement to maximize thermal performance
Solution Approach 1:
The patent applies boiling enhancement coatings with specific surface characteristics (roughness, porosity, or specific geometry) to the chip surface or protective lid. These localized surface modifications create numerous nucleation sites that enhance bubble formation and departure, significantly improving nucleate boiling efficiency and heat transfer coefficients without requiring system-wide architectural changes.
Solution Approach 2:
The patent utilizes porous boiling enhancement coatings on the chip surface or protective lid. These porous structures provide extensive internal surface area and numerous capillary channels that act as nucleation sites for bubble formation. The porous material structure enhances liquid wettability and facilitates rapid bubble departure, thereby maximizing nucleate boiling efficiency and thermal performance.
3Reliability
If a protective lid is used to cover the chip, then chip protection is provided, but heat transfer to the coolant liquid is reduced
Solution Approach 1:
The patent applies boiling enhancement coatings specifically to the outer surface of the protective lid that contacts the coolant liquid. This localized treatment maintains the protective function of the lid while creating an enhanced heat transfer interface. The coating's roughness or porosity structure promotes nucleate boiling on the lid's outer surface, compensating for the thermal barrier effect of the lid itself and maintaining high heat transfer efficiency.
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 BEC significantly enhances thermal conductivity and heat dissipation by increasing the surface area for contact with the coolant liquid, improving heat transfer and boiling efficiency by up to a factor of 15 compared to smooth surfaces, effectively managing the increased heat generated by semiconductor dies.
Implementation Method 1
The BEC forms a roughened surface on the chip or package that enhances nucleate boiling of the coolant liquid in a two-phase immersion-cooling system
Implementation Method 2
The protective lid can be configured to thermally couple to at least one semiconductor die with a thermal interface material
Implementation Method 3
The boiling creates a coolant-liquid vapor in the tank, which is condensed by cooling coils back to liquid form
Data Source
AI summary
Methods to form a boiling enhancement coating (BEC) directly on a protective lid or directly on a semiconductor die are described. The BEC can improve heat dissipation from the protective lid or semiconductor die into a coolant liquid of a two-phase immersion-cooling system. In some cases, a heat spreader is not needed to cool the semiconductor die.