The importance of thermal conductivity:

The thermal conductivity and heat dissipation capabilities of heat sinks are closely associated according to the service life and performance of electronic products.
Materials with high thermal conductivity or thermal interface materials are more capable of directly transferring heat and energy. Thermal conductivity is well known by a number of different names, such as thermo-conductivity, heat transfer coefficient, thermal conductivity coefficient, and heat conduction coefficient.

Key parameters of thermal interface materials - thermal conductivity coefficient:

Key parameters of heat transfer interface materials - Heat transfer coefficient:
The heat transfer coefficient, also known as the thermal conductivity (k), is measured in W/m.K. The thermal conductivity formula is k = (Q)*L/(Ac*ΔT), where k is the thermal conductivity (W/m.k), Q denotes the heat flux (W), L represents the thermal length (m), Ac means the cross-sectional area of the object through which the heat passes (m2), and ΔT is the temperature difference between the hot and cold ends; it is a measure of the amount of heat energy that can be transferred per unit time.
The key parameter in the design of heat transfer interface materials is the heat transfer coefficient. Choosing the best performing (high K-value) product is not always necessary, as hardness, thickness and heat dissipation area are also important factors in the design. All other parameters being equal, the higher the heat transfer coefficient, the more effective the heat transfer management.

Reference table for the heat transfer coefficients of different substances at room temperature:

Material	Thermal conductivity (W/m.K)
Diamond	2300
Silver	429
Copper	401
Gold	317
Aluminum	237
Iron	80.2
Mercury	8.54
Glass	1.4
Brick	0.72
Material	Thermal conductivity (W/m.K)
Water (l)	0.619
Human Skin	0.37
Wood	0.17
Helium	0.152
Soft rubber	0.13
Fiberglass	0.043
Air	0.026
Foamed Rigid Urethane	0.026