At ATS we design many heat sinks. In fact, as of today, we have over 4000 different heat sink designs in our library, plus all our off the shelf designs. It’s likely we have designs that, with minor modifications will fit any thermal challenge. But despite having over 4000+ designs in our library, there are some very basic designs that form the basis for all the variations in the market. In this two-part series, we want to cover these basic designs and give you the pros and cons. At the end of our series, we’ll have a concise cheat sheet for you for easy reference. Here in part 1 we’ll talk about the following heat sink types: Extruded, Stamped, Bonded Fin, and Folded Fin.
Extruded heat sinks are the “utility infielder” of our industry. They are relatively inexpensive, once a design is made the manufacturing is highly automated, and, in most cases, aluminum is the material used. Aluminum is cheap and a relatively good thermal conductor. They are used for most general applications, depending on the design, fin pitch and base thickness they can be low to high performers, and, as I mentioned earlier, they are cost effective. The basic con is they are limited in their dimensions being that they are based on an aluminum extrusion with a given width.
Stamped heat sinks are literally made from a piece of metal being stamped out in a press. A tool is made to the form of the heat sink, then, metal is moved through a stamping machine and the stamp creates the heat sinks. This too is a highly automated process and, as you might guess, once the heat sink design is complete and the prototypes OK’d, then the actual production is a relatively “simple”. Stamped heat sinks are generally use for low power applications since they are typically low in performance. They are cheap, even less expensive than extruded heat sinks.
Bonded fin heat sinks are generally geared towards physically large applications that require moderate performance. Bonded fin heat sinks are made by bonding individual fins of metal to a base. The bonding can be done by a thermal epoxy (somewhat cost-effective) or by brazing (expensive). The main advantage to this type of heat sink is it can be used for large applications, such as a DC-DC Brick, or an electric welder. The main drawback is manufacturing process isn’t automated on the scale of stamped, extruded, or folded fin heat sinks, resulting in a high cost for bonded fin.
Folded fin heat sinks are best when there is ducted air, that is, air flow is directed through a duct of some kind directly at the heat sink. Fin pitch can be optimized in the manufacturing process making this kind of heat sink, with ducted air flow, very high performing. Also, because the heat sink material is folded, there can be a big increase in surface area over which heat can be dissipated. Fold fin heat sinks have high heat flux density [1]. The drawbacks to this type of heat sink are the cost including manufacturing and ducting necessary in your system. In some cases, plastic can be used to create a folded fin heat sink.
In part 2 of our 2 part series on heat sink types, we’ll look at active heat sinks, forged, swaged, single fin assembly and skived.
Need a heat sink like the ones we discussed here? Then please check out our eSHOP to purchase online, visit our heat sink section to see our complete list, or email us at [email protected] with your questions and we’ll respond as quick as we can!
And don’t forget our QoolPCB program, Cool an entire PCB, all heat sinks included, for $50!!
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References:
[1] Heat Flux or Thermal Flux is the rate of heat energy transfer through a surface. Heat flux density is the heat flux unit per area http://en.wikipedia.org/wiki/Heat_flux
