Total Heat Source Size and Heat Density
While the total dissipated is great for rough estimations, the heat source size is also a critical aspect in how heat is applied to your heat sink or other thermal management solution. The heat source size, in addition to the dissipated power, defines the density of a heat load. Heat Density impacts how well a thermal management solution can handle the heat absorbed into the component.
High density heat sources have highly focused heat loads in smaller areas as opposed to a more spread out heat load. Most thermal management solutions rely on conduction to help move heat away from the heat load first, but if there is too much heat applied in a single area, it can accumulate and significantly raise the temperature of the surface and into the device. Like heavy traffic, it can pile up and back up for miles.
Applying Heat Source Size in Aavid Genie
In the Project Conditions of Aavid Genie, you can spread this heat across the entire heat sink base or you can define a specific footprint size to reflect the actual heat density. If you plan on using graphite heat spreaders, vapor chambers, and embedded heat pipes in your heat sink, evenly spreading the total heat load would be a better representation than using the actual area your heat sources.
For applications with multiple devices, you can total up the surface area for multiple loads in the Project Conditions section. This is so Aavid Genie can use an equivalent surface area for the Technology Selection and help pick what material heat sink to use. You’ll be able to update the actual devices and sizes later in the Heat Source Definition page.
Between the total load and heat source size, Aavid Genie can produce a good estimation for the technology selection portion of your heat sink design project.
After you select and design your heat sink, input your flow rate and determine if you will have a duct or flow bypass, you’ll have the ability to place individual devices in the “Heat Source” page. You can drag, copy, and edit your heat sources to more closely match where your heat loads contact your heat sink.