PCB Immersion Cooling Channels for Direct Die Heat Removal
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Solution Overview
Problem
Conventional cooling methods for heat-generating components on printed circuit boards (PCBs) face challenges due to high thermal resistance from intervening layers, making it difficult to maintain proper case or package temperature, especially for high-power electronics like GaN transistors.
Innovation Solution
An embedded PCB with a micro immersion cooling channel that uses a cryogenic coolant and non-conductive fluid, where a lid defines the cooling path and is sealed to the PCB with Indium, allowing direct fluid communication with heat-generating components, eliminating the need for intervening packages and thermal interface materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cold plate cooling methods are used, then cooling capability is provided, but thermal resistance increases due to multiple intervening layers of material
Solution Approach 1:
The patent removes the package and thermal interface material layers that create thermal resistance, allowing the coolant to be in direct contact with the heat-generating die. This extraction of intervening layers eliminates the thermal barriers present in conventional cold plate systems.
Solution Approach 2:
The cooling channel is embedded within the PCB structure itself, with the die nested directly within the cooling channel cavity. This nesting eliminates the need for separate cold plates and thermal interface materials, creating a integrated cooling solution with minimal thermal resistance.
2Reliability
If direct fluid communication with heat-generating components is implemented, then thermal resistance is reduced, but device complexity increases
Solution Approach 1:
The cooling channel is integrated directly into the PCB structure during the PCB fabrication process, merging the cooling system with the electrical circuit board. This consolidation eliminates the need for separate cooling components and reduces overall device complexity despite achieving direct fluid communication.
Solution Approach 2:
The PCB serves dual functions: as the electrical circuit board and as the housing for the cooling channel. This multi-functionality reduces the number of separate components needed, simplifying the overall device structure while enabling direct fluid communication with the heat-generating die.
3Ease of manufacture
If conventional embedded device PCB designs are used, then manufacturing is simplified, but acceptable thermal performance cannot be achieved
Solution Approach 1:
The cooling channel cavity is formed within the PCB during the initial PCB fabrication process, before the die is mounted. This preliminary creation of the cooling structure allows standard PCB manufacturing techniques to be used, maintaining ease of manufacture while enabling superior thermal performance through direct fluid communication.
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 solution enhances cooling performance by reducing thermal resistance, allowing for higher power density, lower thermal cross-talk, and faster temperature control with minimal temperature differential between the coolant and the device, while eliminating the need for conventional cold plates and thermal insulation.
Implementation Method 1
A cooling path extends in a coolant flow direction from an inlet end of the cooling path to an outlet end of the cooling path. The cooling path is in fluid communication with the at least one heat generating component.
Implementation Method 2
This solution enhances cooling performance by reducing thermal resistance, allowing for higher power density, lower thermal cross-talk, and faster temperature control with minimal temperature differential between the coolant and the device
Implementation Method 3
The lid can be sealed to the PCB with a seal element and wherein the lid is joined to the PCB with one or more fasteners. The seal element can include Indium.
Data Source
AI summary
Embodiments have two approaches as follows: (1) Embedded PCB-based fabrication and (2) PCB assembly-based fabrication. An embedded printed circuit board (PCB) type approach involves the creation of a space of coolant direct interconnection, using immersion cooling to link on any type of power semiconductor device hot spots to convectively and evaporatively cool directly. This means fabricating PCB embedded channels, to utilize the microgap between die and PCB as the cooling channel. A printed circuit board (PCB) assembly embodiment includes a PCB having at least one heat generating component. A lid is mounted to the PCB, wherein the lid defines a cooling path therein extending in a coolant flow direction from an inlet end of the cooling path to an outlet end of the cooling path.