Heat Sink Lapping

Warning: While lapping is simple and hard to screw up, you should still know that you must take all responsibility for any mishaps, including sanding the cooler such that the surface becomes uneven and ineffective! Also, if you are using a cooler that's been machined to a really smooth shine already with no apparent imperfections (lots of newer coolers are like this now) we advise you NOT to lap the cooler since you might make things worse. With that said... let's begin!

In the quest for better cooling temperatures the computer aficionado might try a series of mods, fans configurations and heat sinks; some actually mod the heat sink itself. In this article we're going to examine a form of modification; the art of lapping a heat sink, which is smoothing the surface of a heat sink to increase the contact area between it and the CPU. In the manufacturing process the heat sink is machined to quite a smooth surface but still may have some high or low points that cause an uneven contact area. These high and low points are sometimes visible to you in the way of darker or lighter spots on the heat sink. However, even if you don't see spotting on the surface you might be able to see imperfections on the surface, as we did on our Volcano 9, by laying something with a very straight edge (such as a new exacto knife blade) across the surface and holding it up to a light source. If your surface is uneven you should see uneven bits of light breaking at the contact area between your straight edge and heat sink surface. After lapping to a very smooth and flat surface you may still see light still but rather than broken it will be a thinner and uniform line of light with no break points.

To get started you'll need three or for pieces of wet/dry sand paper in grits of 320, 600, 1000 and if you can find a 2000. The first two you should be able to find easily at Home Depot or some other hardware store, the last two however are for fine finishing and you might have to find them at a hobby store or automotive retailer that carries car paint products (such as Canadian Tire). You'll also need to be near a sink or have a cup of water handy. Depending on the kind of surface you have on your cooler you may be able to skip the 320 grit paper - you really only need the lower grit sandpaper if you have a heatsink with a particularly rough surface (such as our Volcano 9), and even then you can get away with just the 600 if you have the patience :).

So in brief you need:

• wet/dry sand paper in 320, 600, 1000, and possibly 2000 grit
• access to water - preferably a sink
• a very flat, even and smooth surface - such as a piece of glass, or a flat table surface
• isopropyl alcohol for cleaning