There are a variety of ways to produce heatsinks and the best type is often determined by the role it will play in the product. However, the most frequent process is extrusion. Extrusion tends to be the most efficient process. Pressure and high temperatures are applied and hot aluminum is pushed through a steel piece to produce the final shape. The best type of heatsinks tend to be extruded ones. LED thermal management aluminum heatsinks are frequently used and produced as they reduce thermal stress.
There are a number of important factors when buying a heatsink but the most important tend to be:
High Heatsink Surface Area
Heat sink manufacturing is a hard process and the best heatsinks tend to have a high surface area as thermal transfer occurs on the surface. Often, producers of high qualify heatsinks ensure that there are many fine fins and that the heatsink has a large surface area.
Good Air Flow
Heatsinks must be designed to efficiently allow air to float through and reach the cooling fins. This is difficult with a high number of fine fins and there will always be a compromise between the number fins and air flow.
Good Transfer of Heat
The most important aspect of a heatsink is that it allows heat from the source to the fins. Heatsinks with thicker fins are better at transferring heat.
Flatness of the Contact Area
The best heatsinks are manufactured with a perfectly flat area where it meets the heat source. This allows the heat source to more easily transfer through the heatsink itself.