Liquid Metal & Its Limits
Cleaning & Sanding
The most important prerequisites for using a liquid metal compound are clean heat sink and spreader surfaces. You can buy the aforementioned kit with the three cleaning liquids, or simply snag some isopropyl alcohol at the drug store. However, stay away from acetone and cleaning naphtha. Even denatured alcohol may contain additives that are detrimental to achieving a clean, degreased surface. Finally, make sure you wait until any remnants of the liquid have evaporated!
If the surface is too smooth, liquid metal can quickly run off of it. Thus, in contrast to what you would do for regular thermal pastes, you may consider roughing the heat sink and spreader up a little bit with a coarse sponge. Just remember that you typically only get enough liquid metal for a couple of tries.
Don't overdo this. If you scrub too hard, the innocent-looking sponge can cause deep grooves. Move in small, graceful circles.
The Perfect Application
Applying the compound is tricky, even though the newest products are a little more like conventional pastes. Still, they are many times more fluid and their composition is still a point of concern, since certain ingredients corrode light metals like aluminum and certain alloys. This could have an adverse effect on thermal conductivity, even causing an insulating layer to form. Copper- and nickel-plated surfaces are alright though, as are heat spreaders.
Once you've roughened up your CPU, you can reasonably apply the paste as drops using a small brush. The amount you'll use varies by CPU size, but plan to go through about half of the tube for larger processors and one-third for smaller ones.
As an alternative, try putting the liquid metal on your CPU away from its processor interface, thus protecting the motherboard from spills. We did this with the chip on our cleaning sponge to ensure none of its pins got bent.
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