Frequently Asked Questions
General Question Topics
Question and Answer
Which type of fan heat sink is better, "air pushing" or "air pulling"?
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.
Which give better performance, black anodized or clear anodized heat sinks?
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
Will the heat sink work without a fan?
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
Heatsink Selection Service
What aluminum material is used for the extrusions (ASTM grade) what anodized finish is
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).