Obviously, the diamond has excellent thermal conductivity. Diamond not only has ultra-high thermal conductivity but also it’s excellent mechanical, optical, acoustic, electrical, and chemical properties, which makes it significantly superior to other materials in terms of heat dissipation of high-power optoelectronic devices. Of course, the cost of the diamond is extremely expensive, which makes it not the preferred material for ordinary heatsink products.
The metal with the best heat dissipation is silver, but it is very soft, which is not conducive to manufacturing high-density devices such as heat sinks. As a precious metal, gold is not a suitable heatsink material because of its expensive cost. The lowest cost material is iron, but its thermal conductivity is only one-third of that of aluminum, which is not a good heatsink material. But it is mostly used for radiators for homes because of good corrosion resistance.
These factors have led to the current use of copper or aluminum as popular heatsink materials.
Copper has better thermal conductivity than aluminum. However, when considering thermal conductivity, the cost is another factor that cannot be ignored. The thermal conductivity of copper is twice that of aluminum, but its density is three times that of aluminum. This means that the weight of a heat sink that provides similar heat flow in copper will increase by about 50%. Actually, many copper heat sinks are overweight beyond design limits on weight. When calculating the cost per ton (copper is currently about 3.5 times the cost of aluminum), and you will find that the cost of copper will be much higher than that of aluminum solutions for the same heat sink design.
Aluminum, especially 6xxx-series aluminum alloy, can be simply extruded into various shapes, including complex heat sinks. Although copper can also be extruded, such as rods, it is very difficult to extrude into the shape of a heat sink, and the cost is also very expensive.
These factors make extruded aluminum heatsink most preferred.
Depending on the design and shape of the heat sink, the aluminum can be designed. Other than the mechanical properties, the metal is easy to manufacture and customize.