Lapping Your Heatsink  

Lapping Your Heatsink

Warning: Lapping your heatsink is a delicate procedure. Improper lapping can cause performance loss or damage to your heatsink. Do not attempt to lap bare microprocessor chips.

Since very few heatsink manufacturers provide a truly flat and even surface on a heatsink, lapping your heatsink can increase performance dramatically by increasing the contact area between your heatsink and your processor. Some people may even want to lap the surface of their processor to further increase the contact area as the processor may also not be perfectly flat. (This only applies to newer processors that are manufactured with a heatspreader. You cannot lap bare microprocessor chips.) SVC.com has put together a extensive heatsink lapping kit that will allow you to refine your heatsink to bring out its full potential.

The premium heatsink lapping kit consists of sandpaper ranging from 400 grit to 2500 grit and a flat lapping surface. The whole process will take approximately 1 hour depending on the condition of your heatsink. Extremely flawed or uneven surfaces will require more time to level out the surface.

Have a flat, hard surface to work on. For small heatsinks and water blocks, you will be able to hold the block on top of the sandpaper. For larger heatsinks, it is best to have a vise or something similar to hold it secure while sanding.

Always start with the lowest grit sandpaper. The 220 grit sandpaper will help shape and remove uneven areas on the heatsink. Be extra careful to keep the sandpaper completely flat and level during this process. If possible, keep the sandpaper on a flat surface and hold the heatsink against the sandpaper. If the heatsink is too large or awkward to be held, use the flat lapping block. Use slow, steady motions to ensure a flat and even finish. As you begin sanding, you will notice that certain parts of the heatsink will make contact with the sandpaper while other parts do not. This is due to the uneven finish left from the manufacturing process. Just keep sanding with the lowest grit sandpaper on a flat surface until all parts come in contact with the sandpaper. You should sand in a back and forth motion and only go in one direction. Once the surface looks even, sand the surface in a a directional perpendicular to your original direction. This will allow you to verify that the surface is flat.

This image illustrates the initial stages of lapping your heatsink. You can clearly see that the nickel plating is being scrubbed off to reveal the copper underneath, you will need to continue this process until you can no longer see any raised nickel plating on your heatsink.

Once the surface is completely flat, move on to the next level of sandpaper and repeat the process. The finer sandpaper should remove all the deeper scratches left over by the previous step. Again, sand in a back and forth motion in one direction and change directions to verify there no scratches left over by the previous sandpaper and that surface is still flat. Use less pressure as you move onto finer grits. Your goal is to remove scratches left by the previous grit.

Repeat the process all the way up to 2500 grit. On the 2500 grit sandpaper, apply minimal pressure and continue to sand until the paper gets "saturated" with dust. After a few minutes of sanding, you should start noticing the material beginning to get shinier and most of the scratches should start to disappear. It is not possible to achieve a true "mirror" shine on 2500 grit sandpaper. There will still be very fine scratches that will be visible upon close inspection. You should be able to achieve the same results as the first picture in this article.

After sanding, carefully wipe off the dust and shavings left behind. If you wish, you may use a polishing compound to get a finer finish. Clean the surface with water, alcohol, or ArctiClean.

Congratulations, you have finished lapping your heatsink. Again, you may choose to use the same process for your processor it it comes with a heatspreader.