Heatsink Lapping

A practical how-to for lapping your heatsink

Introduction

Lapping is the act of sanding the base of your heatsink. By using progressively finer grits of sandpaper you can level and smooth off the base of your HS, and in doing so increase the heat transfer across the heatsink. In some cases this can increase the cooling efficiency of the heatsink and drop temperatures on the chip.

Preparation

We will be using 3-4 various grit of sandpaper. I recommend finding the finest possible grit for the last run, so you can get the heatsink as smooth as possible. Sheets work the best so you can lay out the sandpaper on your workbench. All in all, we are going to need the following materials to lap our heatsink:

• Heatsink :)
• Sandpaper sheets of varying grit - 240, 400 & 600+ should work
• Soft cloth or paper towels
• Canned air (optional)

Lapping

Start out with the lowest grit; place a sheet of sandpaper on the workbench, face up, and then set the heatsink flat on the top of it. Apply good pressure to the heatsink and sand it in an up and down motion. Continue this until the heatsink base rests completely flat on the sandpaper, you want to make sure you flatten the base with the low grit. Once you feel it's quite even, move on to the next higher grit and repeat the process. Continue this for 3-5 minutes (or longer if needed) at every grit until the bottom of the heatsink is completely smooth.

And voila, you're done with the real work! Now you just have to clean the heatsink off. You can rinse the heatsink off, as long as you make sure to dry it completely. Canned air, a hair dryer, a cloth or towels should work fine. Try to use a lint-free cloth to avoid any imperfections on the heatsink. Now go put that sucker on a chip and watch your temps drop!

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