What's the thermal paste

Thermal conductivity
The following is a comparison table of the thermal conductivity of various materials (W / mK):
Air 0.034
2.water 0.58
3. Thermal paste about 0.5 to 10
4. Unbranded lubricants are usually 0.8; some lubricants with added silver and graphite claim to be about 9
5. Alumina (surface layer of aluminum) 35
6. Steel about 40
7. Aluminum 220
8. Copper 390
9. Silver 420

Purpose of thermal paste
Thermal paste is mainly used to assist the heat sink to absorb the heat of the semiconductor components and improve the efficiency of the heat sink. For example, the heat dissipation efficiency of aluminum is 8000 times that of air. A common method in practice is to use thermal paste or thermally conductive paste to fill the unevenness of the metal contact surface, and use thermal paste instead of air as a conductive medium to effectively improve Thermal conductivity of semiconductors or electronic components.