Modular Air Duct Cooling for RF Multi-Layer PWBs
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Solution Overview
Problem
Current thermal management systems for active phased arrays are costly and complex, especially for large aperture sizes, due to the need for individual heat sinks and high-capacity blowers or liquid cooling, which increase weight, complexity, and recurring costs.
Innovation Solution
A modular thermal management system using an air duct assembly with a fan and heat sink to efficiently cool active circuits on a multi-layer RF PWB, reducing thermal resistance and eliminating the need for individual heat sinks, allowing for scalable and cost-effective air cooling of active phased arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If individual finned heat-sinks are attached to each active circuit, then cooling effectiveness is improved, but cost increases significantly
Solution Approach 1:
The patent merges multiple individual heat sinks into a single shared heat sink that serves multiple active circuits. The heat sink is positioned to receive heat from multiple T/R modules simultaneously, eliminating the need for separate heat sinks on each circuit while maintaining effective cooling through its finned structure and strategic placement.
2Temperature
If large capacity blowers are used to force air across heat sinks, then cooling capacity is improved, but system complexity and backpressure increase
Solution Approach 1:
The patent extracts the blower from the phased array system entirely, replacing it with a heat sink design that relies on natural convection and strategic air flow paths. The heat sink is positioned to utilize ambient air flow and natural heat rise, eliminating the need for active blowing mechanisms and their associated complexity.
3Temperature
If liquid cooling is used to maintain operating temperatures, then temperature control is improved, but weight and complexity increase
Solution Approach 1:
The patent replaces the liquid cooling system with an air-based cooling solution. The heat sink is designed to dissipate heat through air convection, eliminating the need for liquid coolant, pumps, and associated plumbing. This substitution dramatically reduces weight while maintaining effective temperature control through the heat sink's finned structure and air flow optimization.
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 system provides a cost-effective and modular approach to cooling active phased arrays, reducing thermal gradients and complexity, enabling efficient heat transfer and maintaining temperatures within the desired range across a wide range of RF output power levels.
Implementation Method 1
A second opposing surface of the heat sink is disposed over and configured to be in thermal contact with a plurality of active circuits
Implementation Method 2
The fan and supply duct are disposed to direct air over a first surface of a heat sink having heat spreading elements projecting therefrom
Data Source
AI summary
A thermal management system includes an air duct assembly comprising a supply air duct having an air inlet opening, a return air duct having an air exit opening and a plurality of distribution air ducts configured to be in fluid communication with the air inlet opening of the supply air duct and with the air exit opening of the return air duct. A fan is disposed within the air duct assembly to direct air from the air inlet opening of the supply air duct through the supply air duct and out the air exit opening of the return air duct. The fan and supply duct are disposed to direct air over a first surface of a heat sink. A second opposing surface of the heat sink is disposed over and configured to be in thermal contact with a plurality of active circuits disposed on a first surface of a radio frequency (RF) multi-layer printing wiring board (PWB).