Heatsink Surface Treatment
After designing all of the crucial features for thermal energy dissipation systems - such as the shape of the fins, the unit size, and the material to be used - the heatsink surface treatment is often given a certain amount of attention by many manufacturers. For aluminum heatsinks, it is common practice to apply an oxide coating over the surface, and thereby endow the device not only with a layer of protection, but also with a distinct color that is more often used for aesthetic purposes than practical ones. The surface treatment for heatsinks that are made out of copper is frequently plated with alloys such as gold, silver and other metals because of their ability to combat deterioration and increase the overall conductivity of the device. Those searching for the right thermal solution will most likely come across a heatsink surface treatment option more than once.
Although there have been arguments made for the use of particular colors over others when anodizing heatsinks made from aluminum, the color choice for oxide plating should be considered primarily aesthetic. That's because the main cause of thermal energy dispersal from heatsinks works by air flowing across their surface - a process called convection - and not by the heat radiating off of the fins. Because of this, the color of a manufacturer's heatsink surface treatment has limited functional value.
One should be cautious before deciding on a copper heatsink surface treatment that is supposed to dramatically increase the device's thermal conductivity. While often times precious metals are used to prevent copper rust and boost the heatsinks overall effectiveness, there seems to be only marginal necessity for this type of heatsink surface treatment. This is first due to the fact that copper will not likely deteriorate in the dry heatsink environment. Secondly, there is not much conductivity added by such a thin layer of surface treatment, making the additional money spent for this feature rather unnecessary.