Heat Sinks

Thought, this issue for a long time without doing Grease topic, and one to the current components properly designed heat, heat is not the same problem that has been fire-breathing dragon P4 era and language; secondly network developed today, word of mouth, "God anointed." nowhere to be seen, Grease principle and material stresses wore not a few words, consumers smarter, less force manufacturers of natural space.

Even so, this thing is full of doubts on the thermal paste is still a few readers, in the end many of the high thermal paste spread difference is not really magic? When will need to replace the thermal grease? How should apply thermal grease is the most appropriate? The spirit of DIY spirit, we specifically collected the common market, buy thermal grease, a total of up to 27 models, and evaluating them one by one, we hope to have a reference direction and basis.

■ Grease the function

In simple terms, the compound exists for one purpose only ─ ─ middle as a heat source and heat sink thermal conductivity "medium." Here we are with a large heat-CPU system is good, CPU heat generated by means of transmission is this: First, the internal heat generated by the operation of the wafer will be transmitted to the CPU cover, and then transfer to the radiator cover base contact surface, and then through the heat sink forms of different conduction (heat pipes, copper, aluminum, water solution), transfer to a piece of fins, fin and finally by heat exchange with the cold air, to achieve the purpose of cooling .

Since the thermal conductivity of the cover the following approach we can not know, so the CPU heat saw the first hurdle is the cover, the reader should read the cover looks like CPU, CPU cover in addition to branded models, code, clock and other information other than , also covered a lot of straight hairline visible grinding marks, surface treatment rather uneven. And even if the GPU or PCH and not of the outer metal cover of the wafer will not be completely smooth surface.

Figure / CPU cover is filled with many visible grinding marks

Again, that is in contact with the heat sink base cover, and removable through the radiator readers will know, obviously, the base contact surface roughness than the CPU does not cover how much you want to well up. Even though many manufacturers introduced advertised mirror base contact surface, but high-expansion microscope view, still full of tiny grooves and gaps, not perfect. Therefore, when the CPU and heat sink base two heterogeneous materials, and uneven after touching face stickers, even if the applied pressure and then a big buckle, middle, or there are many gaps, and these gaps being, will be filled with many "Air . "

FIG / HDT designed base with the contact surface, the groove gap is more obvious.

Thus, in the end base from the CPU heat conduction path, the low thermal conductivity by the obstruction of the air, causing the contact resistance (contact resistance) increased, the cooling efficiency is reduced to the terminal. If you do not understand why the air will hinder heat conduction readers, the following will explain a simple mathematical formula, but you can think about it, life can be isolated from the temperature thermos Why? Is relying on a layer of air is not it? (Of course, be dependent on more advanced thermos vacuum) So, this is why you need with a layer of thermal grease reasons, we need a high thermal conductivity (at least better than air high), but also to the thermal interface material deformation (thermal interface materials) to fill these gaps.