The machining process of the base plane of the heat sink: wire drawing process,Milling of CNC, disc milling process (cutting), polishing, arc-shaped wear marks
Commonly used bottom surface treatment processes include: Wire drawing process (grinding)
The wire drawing process is also the most used heat sink bottom surface treatment process. When drawing the base, a tool with a certain surface roughness and hardness is used. Common ones such as sandpaper, files, etc., are one-way, repeated or rotating friction on the surface of the object, and the cutting effect of the rough surface of the tool is used to remove the protrusions on the processed surface; Of course, polishing the protrusions will also cause scratches on the originally flat surface. Therefore, a gradual process from coarse to fine should be adopted to gradually reduce the roughness of the processed surface.
The characteristics of the drawing process: There are parallel wear marks
Disc milling process (cutting)
The disk milling process refers to milling the surface of the radiator through a high-speed rotating milling cutter after fixing the bottom surface of the radiator. The cutter always rotates in the same plane, so the cut bottom surface is very flat. Similar to the wire drawing process, the finer the tool used in the disc milling process, the higher the flatness accuracy of the milled bottom surface. The manufacturing cost of the disc milling process is relatively high, but it only needs two or three procedures relative to wire drawing, which is time-saving and the effect is relatively ideal.
Disc milling process characteristics: arc-shaped milling marks
Milling of CNC machine tools
The main process used by CNC machine tools to flatten the bottom surface of the heat sink is still milling. But unlike traditional disc milling, the milling cutter of the CNC milling machine can precisely control the relative distance between the milling fin and the heat sink through the single-chip microcomputer. After the milling cutter touches the bottom surface of the heat sink, the two move relative to each other in the horizontal direction to mill the untreated bottom surface left by the tool gap in traditional disc milling, and achieve a complete plane effect. The mirror-like effect can be obtained without any subsequent processing, and the flatness can be less than 0.001mm.
Other flatness processing technology
In addition to the above, there are other processes for the bottom treatment of the radiator, such as polishing. The polishing treatment of "Chemical Passivation" is more for the aesthetic consideration of the radiator. The flatness of the bottom surface of the radiator is improved, and the quality performance is better.
As we said before, no matter how the bottom surface of the radiator is treated, this mechanical process cannot make a completely standard flat surface. The gap or gap between the CPU and the heat sink is always inevitable. The air existing in these gaps has a great influence on the conduction capacity of the radiator. As everyone knows, the thermal resistance of air is very high, so other materials must be used to reduce the thermal resistance, otherwise the conduction performance of the radiator will be greatly reduced, or even unable to function. This is the origin of the heat transfer medium. Its function is to fill the large and small gaps between the heat source such as the CPU and the heat sink, and increase the contact area between the heat source and the heat sink.
