Today we’ll be kicking off a three-part series on choosing and fabricating a heat sink design for thermal management.
For data and voice communications, speed is now the driving factor in the market. As a result, high frequency devices have become a major element for meeting consumer demands. Further, by combining higher packaging density and intelligent (software driven) PCBs there is much more power dissipation at both the component and board level.This situation creates great opportunities and significant challenges for thermal management and electronics packaging.
A first step in addressing thermal challenges is to consider heat sink choice and design. Looking at the market we find a strong presence of extruded heat sinks which can provide only limited thermal performance. Old or off-the-shelf extruded heat sinks do not meet the stringent temperature requirements of today’s ASICs. There’s a sore need for high performance heat sinks that can expand the envelope of heat dissipation in current and near term electronics. With many different types of heat sinks available, the question is: what type of heat sink is suitable for my application?
Heat Sink Types
The general function of a heat sink is the same, irrespective of its fabrication process. Thus we can distinguish between heat sinks by their manufacturing method.
Heat sinks fall into three broad categories:
- Plate-fin: suitable for generally straight airflows
- Pin-fin: suitable for omni-directional airflow
- Foam-fin: suitable for ducted airflow (high pressure drop)
Excluding foam-fins, there are a number of high volume manufacturing processes for creating a heat sink fin field on a flat surface. Many articles are available that describe the details of such manufacturing techniques. Therefore, they are not covered here. The following table below highlights the details of each manufacturing process:
| Bonded | Individual fins are bonded with epoxy to a pre-grooved base |
| Convoluted (folded fin) | Fins are pre-folded and then brazed or soldered to a base plate |
| Die-Casting | Heat sinks are formed as a result of molten metal solidifying in a prefabricated die |
| Extruded | Molten metal is drawn through a die |
| Forged | Molten metal is pressed into a prefabricated mold to form the desired shape |
| Machining | Heat sinks are formed by the machining process |
| Single Fin Assembly | Individual pieces of fin and spacer material are stacked and then brazed to create the desired shape |
| Skived | Fins are “skived†from a solid piece of material |
| Stamped | Metal stamped to form a particular shape |
| Swaged | Individual fins are placed in a pre-grooved base, then a roller swages the sides of the fins to keep them in place |
In part two of “Choosing and Fabricating a Heat Sink Design for Thermal Management” we’ll discuss the pros and cons of each manufacturing technique.
