Direct-to-Chip Boiling Enhancement Coating for Immersion Cooling
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Solution Overview
Problem
As feature sizes decrease in integrated circuits, the heat generated by chips increases, requiring more efficient heat dissipation methods beyond air cooling, particularly in two-phase immersion cooling systems where boiling of coolant liquids is essential for effective heat transfer.
Innovation Solution
Applying a boiling enhancement coating (BEC) directly to the chip or package surface, which can be done through various methods such as spraying, electro-static deposition, or soldering, to create a roughened surface that enhances nucleate boiling of the coolant liquid, increasing the heat transfer coefficient and accelerating boiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If air cooling is used for chip heat dissipation, then the cooling system is simple, but it cannot provide sufficient heat dissipation for high-performance chips with decreased feature sizes
Solution Approach 1:
The patent applies 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 provides significantly higher heat dissipation capability compared to single-phase air cooling, while the immersion configuration maintains relative system simplicity
Solution Approach 2:
The patent uses liquid coolant immersion cooling instead of air cooling, leveraging the superior thermal properties of liquids. The coolant liquid directly contacts the chip surface, enabling efficient heat transfer through conduction and convection, thereby increasing heat dissipation capability
2Power
If a smooth chip surface is used in immersion cooling, then the manufacturing process is simple, but the boiling heat transfer efficiency is insufficient
Solution Approach 1:
The patent applies boiling enhancement coating (BEC) with specific roughness characteristics (Ra = 0.5-5.0 μm) only on the chip surface exposed to the coolant liquid. This localized surface modification enhances nucleate boiling by creating favorable nucleation sites, while the rest of the chip structure maintains its original manufacturing precision
Solution Approach 2:
The patent modifies the surface roughness parameter of the chip by applying BEC, changing the surface topology from smooth to micro-rough. This parameter change creates numerous nucleation sites that enhance bubble formation and departure, thereby improving boiling heat transfer efficiency
3Power
If BEC is applied directly to the chip surface, then heat dissipation is improved, but additional manufacturing steps and complexity are introduced
Solution Approach 1:
The patent applies the boiling enhancement coating to the chip surface before final assembly and packaging. This preliminary action allows the coating to be applied to the bare chip in a controlled environment, and the coating process is integrated into the existing manufacturing workflow, minimizing additional complexity
Solution Approach 2:
The boiling enhancement coating serves multiple functions: it enhances nucleate boiling heat transfer, provides thermal conduction pathways, and maintains structural integrity. This multi-functionality justifies the additional manufacturing step by delivering compounded benefits from a single coating application
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 improves thermal conductivity and heat dissipation by increasing the surface area for contact with the coolant liquid, enhancing the boiling process and thus effectively managing heat from semiconductor dies in immersion-cooling systems.
Implementation Method 1
The BEC forms a roughened surface on the chip or package that enhances nucleate boiling of the coolant liquid
Implementation Method 2
The protective lid can be configured to thermally couple to at least one semiconductor die with a thermal interface material
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.