Vertical Liquid Cooling Channels for Chip Thermal Management

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Solution Overview

Problem

Conventional liquid cooling systems for electronic devices face inefficiencies due to temperature gradients across the chip surface, significant thermal resistance from adhesive materials, and increasing pressure drops with channel length, limiting their effectiveness in high-performance applications.

Innovation Solution

A liquid cooling system with vertically oriented inlet and outlet channels separated by thermally isolating material, directly formed on the chip or chip package using cost-efficient methods like 3D printing, which reduces pressure drop and eliminates thermal interface material resistance by ensuring uniform coolant temperature and efficient heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If conventional liquid cooling channels are used with increasing length to cool larger chip areas, then the cooling coverage is improved, but the pressure drop increases linearly and cooling efficiency decreases due to temperature gradients

Engineering Contradiction:
Improvecooling coverage areaVSAvoidpressure drop
Core Design Contradiction:
Area of stationary objectVSStress or pressure

Solution Approach 1:

The cooling system is divided into multiple independent vertical channels that draw coolant from a common inlet plenum and return to a common outlet plenum. Each channel operates independently with its own pressure drop, preventing the cumulative pressure increase that would occur in series-connected channels. This segmentation allows coverage of larger chip areas without linearly increasing the pressure requirement for each additional channel length.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from conventional planar cooling channels to vertically oriented channels that extend perpendicular to the chip surface. This dimensional change allows coolant to be delivered directly to multiple locations across the chip surface simultaneously, increasing cooling coverage area without proportionally increasing channel length or pressure drop.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Power

If conventional liquid cooling channels are used to increase cooling capacity, then the heat removal capability is improved, but temperature gradients across the chip surface increase due to caloric thermal resistance

Engineering Contradiction:
Improveheat removal capabilityVSAvoidtemperature gradient
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

Multiple independent vertical channels are distributed across the chip surface, each removing heat from a localized region. This segmentation of the cooling function across multiple parallel channels ensures more uniform heat removal across the entire chip surface, reducing temperature gradients while maintaining high total heat removal capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each vertical channel is positioned to cool specific high-heat-flux regions of the chip, providing localized cooling quality matched to the thermal profile. The inlet plenum distributes coolant to all channels at essentially the same temperature, ensuring each channel provides optimal local cooling without being affected by temperature increases in other channels.

Inventive Principle:
Principle #3Local quality

3Strength

If adhesive or thermal interface material is used between the chip and cooler in conventional liquid cooling, then mechanical bonding is achieved, but additional thermal resistance is introduced that significantly reduces cooling efficiency

Engineering Contradiction:
Improvemechanical bondingVSAvoidthermal resistance
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The patent extracts and eliminates the thermal interface material layer from the cooling system by directly forming the vertical cooling channels into the chip substrate itself. This removal of the adhesive/TIM layer eliminates the associated thermal resistance while the chip substrate provides the necessary mechanical structure to contain and support the cooling channels.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The cooling channel structure is merged directly with the chip substrate through direct formation processes, combining the structural support function and the heat transfer function into a single integrated component. This merging eliminates the need for separate adhesive layers or thermal interface materials between the cooling channels and the chip.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of operation

If conventional separate cooling units are mounted to chips, then modular assembly is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvemodular assemblyVSAvoidmanufacturing complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The cooling channels are merged directly into the chip substrate through direct formation processes such as molding or 3D printing, combining what would traditionally be separate components into a single integrated structure. This integration simplifies manufacturing by reducing the number of assembly steps and components, while the modular nature of the vertical channel design maintains ease of operation and scalability.

Inventive Principle:
Principle #5Merging (Combining)

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 approach enhances cooling performance, reduces power consumption, and allows for scalable designs with localized, accurate cooling, effectively addressing the limitations of conventional liquid cooling systems.

Implementation Method 1

a plurality of inlet cooling channels fluidically connected to the coolant feeding channel and arranged vertically for impinging a liquid coolant directly on said main surface of the chip

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

allowing interaction between the liquid coolant provided through the inlet cooling channels and the main surface of the chip

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 3

the vertically oriented inlet cooling channels being substantially parallel to the vertically oriented outlet cooling channels and being separated by a thermally isolating material

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 4

an outlet plenum comprising a coolant removal channel and a plurality of outlet cooling channels arranged vertically for guiding the liquid coolant, after impinging of the coolant on the main surface to be cooled of the chip, towards the coolant removing channel

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3188230B1Liquid cooling of electronic devices
Publication Date: 2020.09.02 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)
  • EP3188230B1 patent drawingFigure 1~2
  • EP3188230B1 patent drawingFigure 3~4
  • EP3188230B1 patent drawingFigure 5~6

AI summary

A liquid cooling system for cooling an electronic device comprising a chip or a chip package comprising a chip is described. The liquid cooling system comprises an inlet plenum comprising a coolant feeding channel oriented substantially parallel with the plane of a main surface to be cooled of the chip and a plurality of inlet cooling channels fluidically connected to the coolant feeding channel and arranged vertically for impinging a liquid coolant directly on said main surface of the chip. The vertically oriented inlet cooling channels are substantially parallel to vertically oriented outlet cooling channels and are separated by a thermally isolating material. The liquid cooling system further comprises at least one cavity wherein a plurality of inlet and outlet cooling channels end. The cavity is arranged for allowing interaction between the liquid coolant and the main surface of the chip and thus comprises a heat transfer region.