CPU radiator mainstream process – heat pipe process (reflow soldering)

What is a heat pipe ?

A heat pipe is a passive heat transfer element with extremely high thermal conductivity. The heat pipe uses the phase change principle and capillary action to make its heat transfer efficiency hundreds to thousands of times higher than that of pure copper of the same material. A heat pipe is a vacuum copper tube, and the working liquid filled in it is the medium for heat transfer.

There is a wick structure on the wall of the heat pipe. The capillary force generated by the wick allows the condensed liquid to return from the condensation end to the evaporation end. Because the heat pipe is evacuated and the liquid is injected before sealing, the pressure inside the heat pipe is determined by the vapor pressure of the working liquid after evaporation. As long as the surface of the heat pipe is heated, the working liquid will evaporate.

How heat pipes work?

The heat absorbing end is heated and the internal liquid undergoes phase change (liquid to gas);

The condensation end dissipates heat and the internal gas undergoes a phase change (gas to liquid);

The condensate flows back through the liquid through capillary action;

Note: The heat pipe adopts a vacuum design inside, and the liquid can reach boiling point at 35℃ under negative pressure;

Heat pipe working process

1. Heat is transferred from the heat source to the (liquid-vapor) interface through the heat pipe wall and the wick filled with working liquid;
2. Liquid evaporates at the (liquid-vapor) interface in the evaporation section;
3. Steam in the steam chamber flows from the evaporation section to the condensation section;
4. Steam condenses on the vapor-liquid interface in the condensation section:
5. Heat is transferred from the (vapor-liquid) interface to the cold source through the wick, liquid and pipe wall:
6. The condensed working liquid flows back to the evaporation section due to capillary action in the wick.

Reflow soldering process + heat pipe technology

It is generally used in radiators made of copper. The principle is to make thin copper sheets into fins and connect them well to the base. This principle is welding technology. However, welding technology can no longer meet the needs of today’s sophisticated all-copper radiators.

Therefore, a novel reflow soldering technology has become a necessary process for manufacturing precision heat sinks today. In summary, reflow soldering is to accurately set the temperature and time parameters of soldering through a computer so that the solder paste and the metal being soldered are in full contact. The application of this technology ensures the excellent heat dissipation performance of the pure copper heat sink. Of course, the reflow soldering process has now been gradually applied to the aluminum fin + copper bottom process, so the reflow soldering process + heat pipe technology is the best air-cooled CPU heat sink with the best performance.

CPU Cooler Bottom Technology

Usually there are three kinds of bottom processing technologies for our radiator:

1. Wire drawing: It is the process of grinding the metal surface with an emery belt;

2. Polishing: It is the process of polishing the metal surface using a non-woven wheel (Non-Woven Wheel);

3. Milling bottom: use a milling cutter to process the bottom surface;

There is also the direct contact core heat pipe technology we mentioned above, as well as rolling technology, etc.