Thermal Management Concerns

Larger and larger areas of copper do not help, especially with thinner copper. A point of diminishing returns is reached for a square copper area of size 1 inch x 1 inch. Some improvement continues until about 3 inches (on either side), especially for 2-oz boards and better. But beyond that, external heatsinks are required. A reasonable practical value attainable for the thermal resistance (from the case of the power device to the ambient) is about 30°C/W. That means 30°C rise for every watt of dissipation inside the IC. 

To calculate the required copper area, we can use as a good approximation the following empirical equation for the required copper area  

Here P is in watts and Rth is the desired thermal resistance in °C/W (degrees Centigrade per Watt). 

For example, suppose the estimated dissipation is 1.5 W. We want to ensure that, at a worst-case ambient of 55°C, the case of the part does not rise above 100°C (safe temperature for the PCB material — do not exceed ). Therefore the Rth we are looking for here is 

If this area is square in shape, the length of each side needs to be 6.7905 = 2.6 inches. 

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The heat balances given in Sections 6.3.1, 6.3.2, 6.3.3, and 6.3.4 are preliminary and are provided only for baseline comparisons. To enable comparison of the one, two, three, and four Brayton systems, the heat balances assume the same set of input parameters. The assumed operating parameters do not represent the optimal set of operating conditions for any particular configuration. Each of the heat balances incorporate piping system pressure losses based on the preliminary arrangements described in Section 5 of this report which have not been optimized for pressure drop, mass, or thermal management concerns. 

Thermal management concerns identified during the pre-conceptual efforts for the Reactor Coolant and Plant Structure segments include the following ... 

Due to their isotropic radiation, LPP sources allow for the use of normal incident collectors thus, higher collection efficiency can be achieved with LLP sources as opposed to DPP sources, which tend to be directional. Because LPP sources do not require electrodes, there is no concern about electrode debris being generated from them. In addition, LLP sources have potential for easier and better thermal management than DPP sources because the plasma they generate is isolated from the collection optics, which is designed to capture the emission from the plasma and relay it to the intermediate focus from where it is relayed to the exposure tool. 

This paper focuses on problems concerning the thermal management when using a fuel cell in a portable device. They can be summarized as follows ... 

The development of modern technologies demands electronic devices with superior performance reflected in multiplication of their functionality (Tong 2011). One of the challenges in electronic packaging is to overcome barriers concerning thermal management, which is a common problem that can reduce... 

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