In part 1 of our 3 part series, “Choosing and Fabricating a Heat Sink Design for Thermal Management” we discussed different heat sink manufacturing methods. Today we want to discuss the pros and cons of each method so you can make an educated decision on which method to choose.
The pros and cons of each manufacturing technique:
| Type | Best for | Thermal Resistance | Pros | Cons |
| Bonded | Large applications | High | Close tolerances | Expensive |
| Convoluted (folded) fin | Ducted air | High at low flows and low at high flows | High heat-flux density | Expensive, needs ducting |
| Die-cast | Low power applications | High | Can be inexpensive | Low thermal conductivity and expensive die charge |
| Extruded | Most applications | Varies | Versatile | Limited size |
| Forged | Many applications | Moderate | Inexpensive | Limited in design and flow management |
| Machining | Prototypes | Design dependent | Quickly available for testing | High aspect ratio fins difficult to machine – inconsistent fin geometry |
| Single Fin Assembly (SFA) | All applications | Very low | Light weight and low profile with high degree of flow | Expensive |
| Skived | Many applications | Moderate | Close tolerance | Thick base, higher weight, directionally sensitive |
| Stamped | Low Power | High | Inexpensive | Low performance |
| Swaged | High power applications | Medium | Good for power devices | Heavy and bulky, limited ability for flow management |
The manufacturing process has a direct impact on a heat sink’s thermal performance. This stems from the number of fins that can be produced by a given manufacturing technique and from the interfacial resistances created when using that process. Bonded fin and swaging assembly techniques introduce a third material between the fins and the base. Single-fin assembly (SFA) places a third material in between the fins. Although SFA is a brazing process and the metallurgical joints very close to solid, nevertheless, all three of these techniques are impacted by the presence of the third material. Among other methods, stamped, extrusion and die-casting are perhaps the oldest technologies for high volume production. Most heat sinks on the market are made by such processes.
More recent heat sink fabricating methods were developed to meet the need for more fins on a flat surface. SFA, micro die-casting and forging produce higher performing heat sinks suitable for high power application. Of the three, SFA can produce the highest number of fins per linear length because of its manufacturing process. (Advanced Thermal Solutions, Inc. has made SFA heat sinks with 26 fins per cm, or 67 fins per inch.). Manufacturing technology has advanced enough to produce high aspect ratio as well as high fin count heat sinks.
In part 3 we’ll conclude our series on “Choosing and Fabricating a Heat Sink Design” with the salient features of high performance heat sinks.
