Creating Larger Aluminum Heat Sink Extrusions

With continued advancement in consumer electronics and rapid growing LED lighting options, new products require increased energy demands with a smaller footprint. Increased power can cause heat that is detrimental to electronics.

Dealing with that heat presents a thermal management challenge. The most common technology for electronic modules is extruded aluminum heatsinks. There are two categories of extruded aluminum heatsinks – high ratio and low fin.

The fin ratio compares the fin height to the width between the fins. Typically, extruded aluminum heatsinks have a ratio of 6:1. That ratio does not meet most power electronics requirements. The typical ratio needed ranges from 12:1 to 19:1.

A greater fin ratio indicates greater surface area. Greater surface areas mean larger amounts of heat can be removed. Specific technology and experience are required for heat sink extrusions with higher ratios. It's hard to find heat sink extrusions that are more than 24 inches wide.

Heat sink extrusions are thermal devices made of a solid piece of aluminum. Insulators are eliminated and make the heat sink extrusions more thermally efficient. Most heat sink extrusion applications use natural convection, eliminating the need for fans.

Bonded fin heat sinks that have a higher aspect ratio are common means to overcome the heat sink extrusion ratio limitations when higher ratios are required. Friction stir welding (FSW) offers a different approach.

It is eight percent more efficient and has more options. Combining FSW and the extrusion process, heat sink ratios that exceed 40:1 are possible. The combination allows for

Maximum flexibility regarding fin geometry and ratio

 The heat sink extrusions footprint

 Production of large scale heatsinks

 The custom extruded aluminum heatsinks replace bonded fin heatsink coil aspects. FSW is also used for liquid cold plates to seal them efficiently while allowing other features to be added to base plates at a lower cost.

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