Questions and Answers

According to our testing, the induction type (air pulling) showed better results versus the expulsion type (air pushing). Several factors contribute to this. We utilized an intake cover in our testing that forces the air to enter through the lower, hotter, section of the heat sink. The intake cover is also set 5mm above the top of the fins. This creates a negative pressure area that ensures all of the fins receive airflow, eliminating the dead spot from the center fan hub. However, if another heat source is located near the heat sink, heated air could be drawn into the heat sink and affect performance. The final choice must be made depending on the local environment.

The color itself will have little impact on performance, even under natural convection, zero airflow, conditions. However, the surface finish/emissivity will have a significant impact under these conditions. A shiny surface, like bare aluminum, will provide a relatively low surface emissivity. An anodized surface will create a relatively dull surface finish that will provide a relatively high surface emissivity. This would be true whether the anodized surface is clear or black. A surface with a better emissivity will improve the heat sink’s ability to dissipate heat by radiation.
Surface Treatment Options

The performance of a heat sink is dependent on many factors. In selecting a heat sink, factors such as space limitations, airflow, air temperature, and maximum case/junction temperature all need to be considered. For more information on selecting a heat sink, see our Online Catalog and Heatsink Selection Service.

We use A6063 Aluminum. ASTM-B-221 QQ-A-200/9. Our anodized finishes are typically black or clear per Mil-A-8625F (Type II, Class 2/Class1).