Copper Foam Heatsink II

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SUMMARY: Copper foam as a heatsink material continues to tantalize.

I reported earlier on using a metallic copper foam material in a Copper Foam Heatsink. Test results were encouraging, especially considering the small footprint of the heatsink, for 1U applications.

I received emails asking about other design configurations and we decided to try another pass with this one:

Cu Foam

Cu Foam

This was adapted from an existing heatsink featuring a copper base and aluminum fins. The copper foam was applied onto this base. With more surface area of the copper foam exposed to airflow through the fins, it was supposed that this would be a good performer.

This test used the CPU Die Simulator which gives results that are unaffected by motherboard influences. This is a small die test and typically results in higher C/Ws than with the P4 rig. I used a 15 x 70 mm, 4200 rpm, fan mounted directly on top of the copper foam.

Test Results

Heatsink

Die Temp

Ambient Temp

Delta

C/W

Cu Foam

57.0

22.9

34.1

0.49

Interpreting C/W: For every watt (CPUw) that the CPU
consumes, the HSF will limit the CPU’s temperature rise to (C/W x CPUw)
plus the temperature at the HSF’s fan inlet. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that CPU temp will increase 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.

Not a barn burner, but what I found interesting is that taking a look at similar C/Ws in the Heatsink Ranking, the copper foam heatsink held its own against some larger units, and then some. As a possible 1U solution, an optimized copper foam heatsink could have some merit for space constrained applications – possibly turning in a C/W around 0.40.

CONCLUSIONS

An interesting material – optimization will most likely require some “out of the box” thinking, but the potential for a very competitive, small heatsink appears bright.

However, a number of readers have noted that dust clogging could be a problem with this material due to its density. We thought about this and I would think that some type of dust filter over the fan would help.

Email Joe

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