Surface Roughness Comparator:

Surface finish is an important factor that we all look for when holding a new heatsink. Flipping a cooler over to see how well the base has been machined is a quick way to judge the attention to detail that was put into making it. The following FrostyTech Surface Roughness Comparator offers a concise cross section common machine surface finishes. Not every heatsink base will fit into the envelope of this gage, but it does offer a very handy set of representations.

This commercially available gage has 22 machined surfaces from 2 to 500 microinches; Lapped (2, 4, and 8 µ" RA), Ground (8, 16, 32, and 63 µ" RA), Blanchard Ground (16 and 32 µ" RA), Shape Turned (32, 63, 125, 250, and 500 µ" RA), Profiled (63, 125, 250, and 500 µ" RA), and Milled (63, 125, 250, and 500 µ" RA).

FrostyTech Surface Roughness Comparator
the base of a heatsink plays an important role in how well the cooling apparatus interfaces with the processor. poor surface roughness will affect a good heatsink just as much as a good surface finish will improve thermal conductivity. in an effort to put a more quantitative spin on the comments we provide about base finishes, frostytech has begun using a surface roughness comparator. move your mouse over the image above to see an example at right. numbers are in microinches, and finishes from 2 microinches to 32 microinches are excellent-to-good.
Evaluation Notes:
The Aopen ACP4LC heatsink had a surface roughness of approximately 32M, so it is well within the acceptable range of surface finishes.