Skived Fin heat sinks can be an alternative to extruded heat sinks when looking for a fin density which can’t be achieved by extrusion technology. Skived heat sinks can be manufactured from either copper or aluminum and usually have 0.5 (0.020”) thick fins. Skived heat sinks are produced using a series of sharp knives that, as they pass over the material, curl up a small thickness of metal which is then bent vertically to form the fin. Skived fins are produced from a bar of material which is approximately 16 feet in length and then cut to length as required by the final application. The final heat sink can be machined using normal fabrication techniques. Because of the thin fins, care must be taken in handling to prevent damage. It is suggested that a shroud be placed over the fins to help prevent damage.
Zipper Fin heat sinks can be an alternative to both extrusion and skived when looking for high density structure. Unlike skived fin, a zipper fin heat sink is an assembly of a base and a fin stack that are soldered or bonded together. The fin stack is created using a set of individually stamped fins which are joined together in several locations along the top and bottom edges. The location and number of joining features are determined by the design. Since the fins are stamped individually, they may have any shape and include other stamped features. While zipper fins are most often used with a base plate, they can also be used with heat pipes. A hole(s) is/are stamped into the fins and the fin stack set is placed on a series of heat pipes to form the heat sink. This type of construction is generally found in CPU coolers. Zipper fins can be manufactured from either copper or aluminum and it is possible to mix the different materials within a fin stack. The base can be either aluminum or copper as well. Depending upon the materials used, the finish is either a nickel plate or a chromate, either of which will improve the thermal performance and provide environmental protection.