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How To: Lap A Heat Sink
By Robert | March 25, 2007
If you know what lapping a heat sink means then you will most likely know what the advantages are. Just in case you don’t I will tell you anyway.
When you buy an aftermarket heat sink or even a stock heat sink, if you look at the bottom you will see that it will have a lot of very little grooves and will not be 100% flat. Some heats sinks are better than other but almost all could use a good tidy up.
Here I will show you the process of lapping your heat sink smooth so it has full contact on the heat spreader of the CPU which will increase the heat transfer from the CPU though to the heat sink and in turn giving you a cooler CPU.
Here you can see the heat sink before it has been lapped. To the naked eye it looks pretty good but what you eye can’t see is that it is not flat and also has some very deep groves. Once the lapping process has been completed you should be able to see your face reflected on the bottom of the heat sink.
Here you can see after placing the non lapped heat sink on the heat spreader of the CPU that the thermal paste has not spread evenly across the heat spreader and has a large build up on the left and right side. This means that the left and right side of the heat sink are higher than the middle and will not be making full contact with the CPU. This will result in higher temperatures. After we have finished lapping the heat sink you should see a very even spread of thermal paste and no builds up on any of the side. By placing the heat sink on the CPU first lets you know what areas of the heat sink need working on. In this case the middle needs to be sanded down to be even with the left and right sides.
These are the tools you will need to complete the job. You will need: A heat sink, CPU, etc. Some wet-dry sandpaper of 200, 400, 800, 1200 and 2000 grit. A flat glass surface to work on. A roll of duct tape. An old rag and a couple of hours of your time. You will also need to be very careful.
Now what you will need to do is tape the rougher grade sand paper down to your desk. You have to make sure that it is stuck down very tight and has as little movement as possible as you being lapping the heat sink across the sand paper not rubbing the sand paper on the sand paper.
At this stage you will need to get the hang of a good lapping technique. Hold the heat sink base down on the sand paper and drag it back and forth until you fill like it is getting close to flat. Now take you flat piece of glass and sit your heat sink on top and try and rock it side to side. If you can’t feel any movement then it is time to move on to the next step. If it feels like it is still moving then go back and lap it a bit more and try again.
Once you feel like you have got it as flat as possible with the roughest sand paper then slowly start going down though the finer grades until it is as smooth and shinny as possible.
If everything has gone to plan your heat sink should look something like that. As you can see there is a very nice reflection on the base and very few scratches. You could sit there for days and never make it perfect but you will also see that you will get to a point that the more you work on it the worst it gets. Just keeps going at it until you are happy with the results.
You should see a very nice drop in temps over your non-lapped heat sink but don’t expect it to be the answer to all you cooling problem. There is still nothing better than a good set of fans.
I hope this has been helpful.
*Images courtesy of OCAU
Topics: Hardware Mods |
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