Aavid Genie explores 6 different heat sink types: Extruded, Bonded Fin Assembly, Brazed Fin Assembly, Folded Fin Assembly, Skived Fin, and Zipper Fin Assemblies. Defining heat sink materials is based off the heat sink’s manufacturing method. Assembled heat sinks may have limitations on how they’re joined together.
Single Piece Heat Sinks
Extruded and skived fin heat sinks are created with a single piece of metal. Standard,commercially available extrusions are only available in aluminum. So Aavid Genie will only use aluminum thermal properties when estimating and calculating your heat sink performance.
Skived fin heat sinks are produced from either aluminum and copper. Aavid Genie allows you to select between these two materials, but not mix them. Since the fins are cut and folded up from the base, you can only use a single metal in a skived fin heat sink.
Heat Sink Assemblies
Aavid Genie considers other heat sinks which are considered assemblies because the base and the fins must be joined. The process that joins them or how the fins are made determines how Aavid Genie classifies they. Bonded and Brazed fin assemblies are named by the bonding process used to connect the fins and base. Folded and Zipper fin assemblies are named by the type of fins that are attached to the base.
Aavid Genie assumes bonded fin heat sinks are aluminum only. The thermal epoxy used to join the fins and base doesn’t adhere well to copper surfaces. This is why you don’t have the option of changing the material over to copper for bonded fins in the Genie. When Aavid Genie simulates a bonded fin heat sink, it accounts for the interface resistance from the thermal epoxy layer.
Brazed fin heat sink assemblies are more flexible when it comes to material selection. Aavid Genie also groups soldered assemblies into this group for mixed materials (we’ll do another post explaining boding methods.). Keep in mind, aluminum has a hearty oxide layer that resists soldering, so it’s typically treated and plated with a more solderable layer like nickel.
Folded and Zipper Fin Heat Sinks
Folded and Zipper fins are also joined to a base to create a heat sink assembly using either epoxy, solder or braze alloy depending upon the materials being used. While the most common folded fin and zipper fin stacks are made with aluminum or copper, it’s not surprising to see stainless steel, cupro nickel, titanium, inconel and other nickel alloys used for these fins.
Custom Materials within Aavid Genie
You have flexibility of joining methods between the base and the fins for Brazed, Folded, or Zipper fin heat sink assemblies. Aavid Genie reflects that choice by enabling you to define a custom material by providing the material density and material conductivity. You can define specific materials for your base, fins, or both depending upon your application needs. This option is available in the “Heat Sink Design” page in Aavid Genie.
Defining heat sink materials is a key parameter to consider while you’re working on your custom heat sink design. Take some time to think about your end application. It might be helpful to take some more time to consider the Technology Matrix page in the Genie and look at your recommended options. Do you need help defining heat sink materials for your application? Contact Aavid Design Engineers to discuss your product and application conditions.
What are some of the weirdest materials you’ve seen used for a heat sink? Let us know at firstname.lastname@example.org!