I was reluctant to review a heat sink lapping kit. Why? Because it sounded like a lot of work! I could see myself at the grindstone... er ....lapstone for several hours, moving my arms in the arc of theta (an engineering joke). And you know what? I wasn't that far off! Man, am I tired. I mean worn out. Wasted. Hosed. But don't jump to the end of this review just yet. Maybe, just maybe, this is a product you need. Perhaps there is a silver lining to this cloud...
Packaging and Contents
As you can see in figure 1, you get a small package, basically consisting of sheets of sandpaper. There are several versions of the Heat Sink Lapping Kit, including a Premium version (which we are reviewing, shown on the left), and a standard version (also shown in figure 1, on the right side) which we aren't reviewing since the Premium version contains everything found in the standard version. The folks at EasyPCKits have several other items that are worth checking out, so please pay them a visit. The prices are very reasonable, even for a cheapskate like myself!
In figure 2, you can see what is contained in the Premium kit. Basically it's a small plate of glass, a small container of Artic Silver Thermal compound, and one each of the 1/4 sheets of the following grit sandpapers: 400, 600, 800, 1000, 40 micron (yellow), 25 micron (green), 20 micron (blue), 15 micron (peach), and my personal favorite, 10 micron (green). The standard kit has fewer sheets of sandpaper, and no glass plate or Artic Silver Thermal compound.
If you follow the included instructions, which state that they should be read carefully before you begin (they are right), you need to slightly bevel the four corners of your CPU heat sink (aka CPU cooler) so it won't catch and tear the sandpaper. That was easy enough. You also need to have a bucket of water, and some paper towels or newspaper. This is gonna get messy! But before we begin, let me introduce you to our victim...er...volunteer, the Kanie Hedgehog Type-W Socket A all copper CPU heat sink (figure 3).
Prior to lapping, lets see how nice the stock finish is on the Kanie CPU heat sink by looking at a reflection of my spousal unit. Note how nice the reflection is. We shall label this intial spousal reflection factor (srf) assessment with 0.8 as a baseline. A 1.0 would be a mirror finish, and a 0.5 would be a measure of my clear conscience. Maybe I should be leaving well enough alone...
I use a little muscle to get what I need:
Now for the part I dreaded; sanding the CPU heat sink with progressively finer-grit sandpaper until my arm was ready to fall off. It may not seem difficult for you to sand something for five minutes, but it is particularily stressful for me due to an old motorcycle injury to my right wrist - it was basically shattered back in 1983. I have about 45 degrees of movement and daily low-level pain in this wrist, so anything that stresses the joint (heavy lifting, applying pressure, etc.) will generate mid-level pain for a few days. But hey, enough about my problems! That's what the forums are for.
As you can see in figure 5, I've performed some extensive sanding with the 400 grit sandpaper. You simply must use water (wet sanding), as your CPU heat sink will catch and tear the paper if it's dry. But I see a problem here; do you? Yep, the surface wasn't flat. That is why the Premium lapping kit is a very good idea, if you have decided to lap your CPU heat sink. The small plate of glass included with the Premium Heat Sink Lapping Kit is a very flat surface, and as you start sanding with this glass as your support for the sandpaper, it will reveal how flat the bottom of your CPU heat sink really is. Apparently, my Kanie Hedgehog Type-W heat sink wasn't very flat at all. Keep an eye on that center area as we progress to finer-grit sandpapers...
With figure 6, you can see that time has elapsed, and now we see the result of about 35 minutes of wet sanding. We have moved up to 1000 grit sandpaper, but that center area is still not right. Did I do something wrong? Yes I did; thanks for asking! I should have kept going with the 400 grit sandpaper. I should have sanded until the whole surface was identical in texture. But I couldn't do it. I was simply too exhausted after 25 minutes with 400 grit. I bet you could do better. In fact, I challenge you to do better...
Is it done yet?
Figure 7: Click image for a larger view
One problem that requires experience to resolve is knowing when you have sanded enough to move on to the next grit. In figure 7, we are up to 25 microns (0.025) sandpaper, and two things are now apparent. First, that center section isn't going to look like the outside edges unless I go back to 400 grit sandpaper for a return engagement (I don't think so....). Second, the quality of these pieces of sandpaper is very good - consistent abrasion qualities, and they last a good long time. The Energizer Bunny could learn a thing or two from EasyPCKits .
Ok, figure 8 shows you the best I could do, after finishing up with 10 micron sandpaper. The spousal reflection factor (srf) is worse than what I began with. I would say we have dropped down to a 0.6 assessment. As a result, I won't be mounting this heat sink on my wife's computer! Also, we all know how copper will oxidize over time. I don't know if the previous surface (prior to sanding) was coated with anyting to prevent oxidation, but we now know that there is no longer any coating there to prevent possible oxidation. Time will tell if this is an issue.
I've only scratched the surface (I've been waiting to say that) of how far you can go with the Premium Heat Sink Lapping Kit. I didn't go far enough, and I'm the first to admit it. I now have a much flatter surface where the heat sink meets the CPU die, but I messed up the smoothness of that surface (as measured by reflectivity) because I ran out of steam with the 400 grit sandpaper. Would I use the heat sink again? Yes, as quality thermal interface compound, such as the small tube of Artic Silver that EasyPCKits included with the Premium kit, will fill those small voids in the surface. Because the heat sink is now flatter, I might even get better contact across the CPU die surface. The larger the CPU die, the more likely the contact between heat sink and die has increased. But a shiny surface is the desired outcome, so please learn from my experience and take a day or two off so you can finish the job after getting some rest.