Skived, Zipper Fin
Forced convection is a mechanism in which fluid motion is generated by an external source like a pump, fan, or other device. While the term forced convection can be used to refer to any fluid, it is most commonly associated with forced air cooling. Because of the usually high airspeeds associated with forced convection, significant amounts of heat can be transported quickly and efficiently. The amount of surface area on the heat sink is an important factor in helping meet the desired thermal performance, but too much surface area will cause the heat sink to have a large pressure drop. The greater the drop in pressure, the greater the strain put on the fan, which results in decreased fan performance. Wakefield-Vette engineers will help find the optimal operation point to achieve your thermal requirements.
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.