Heatsink Guide - The Basics of Cooling & Heatsink Technology

The production method

Different heatsink manufacturers have come up with many different production methods. Let's have a look at some of the popular heatsink designs:
 
 

Extruded heatsink	"Folded fin" heatsink
"Bonded fin" heatsink	Die-cast heatsink
Cold forged heatsink	Milled / cut heatsink

• Extrusion is the most popular production method for heatsinks. It is inexpensive, and quite fine structures can be created using this production method. The liquid aluminum is pressed through a form, so that a long stick with the shape of the heatsink is created. After this "heatsink stick" stick has cooled down, it is cut into pieces the size of the heatsink. However, there are certain limitations with this production method. For example, a heatsink shape like the one shown in the fourth image could not be produced with this method.
  
• Folded fin design: Here, the fins are made of a thin metal plate, which is folded, and bonded onto a base plate. The advantage is that the fins are hollow, so they have a bigger surface and allow better airflow (and thus better cooling). Using this design, light, compact, and still very efficient coolers can be designed. The disadvantage is that heatsinks with folded fins are more expensive to produce, and therefore only a few manufacturers offer coolers using this design.
   
• Bonded fin design: This design is very similar to the "folded fin design", except that here, many smaller metal plates are bonded onto the base plate, instead of one large folded plate.
   
• Die casting: This production method gives the heatsink designer a lot of freedom, and allows for certain heatsink shapes that cannot be produced using extrusion. However, the fins of a die cast heatsink cannot be very fine.
   
• Cold forging: This is a relatively exotic production method. It's included here because a very popular heatsink, the Alpha PFH6035MUC, is produced using this method. This technology is very suitable for heatsinks with many small pin fins.
   
• Milling: Like cold forging, this production method is quite unusual for heatsinks. It's included in the chart because the heatsinks by HP PolarLogic are produced this way. Milling leaves the heatsink designers a lot of freedom, too, but it is expensive.

Of course, this is not an exhaustive list, but almost all CPU heatsinks available on the market today are produced with one of the above production methods.