There is a direct, linear relationship between the thickness ofthe material and heat flow which can be transported through the material.
Rule of thumb: If an equal amount of heat needs to be transported through material of double thickness, the thermal conductivity must also be doubled.
So the advantage of Kapton MT+: very good thermal conductivity with minimal material thickness and very good dielectric strength
Important: this statement refers only to transport within the homogeneous material - thermal transfer resistance is not considered.
The thermal conductivity of a test material is determined according to ASTM D5470 as follows:A heated metal block provides the heat source. Another block of metal is located underneath (cooled if necessary)serving as a heat sink and separated by the heat-conducting material. Temperature sensors are mounted just above and below the heat-conducting material.
Once a stable heat flow has been set, the temperature difference generated by the test material is determined. The thermal conductivity is then calculated from this.
Advantage of this method over the LASER Flash Method: The roughness on the surface of the material is also measured. This is important because the contact resistance at the interfaces of the different materials always plays a role in a real installation situation.
Heat transfer, for example from the housing of a power transistor to an aluminium heatsink, can be quite bad. Surface roughness reduces the direct contact area necessary for thermal conduction by about 20-40%.
Using thermally conductive wax (phase change material, PCM), for example, can avoid this pitfall. The wax, solid at room temperature, melts when used for the first time and is filling out the cavities. The heat can flow without interruptions by air pockets.
The result: reduction of heat transfer resistance using thermally conductive coatings!