From a decarbonization perspective, the electrification of automobiles and the inverter control of air conditioning and hot water supply systems are becoming increasingly important. Power devices, which are indispensable for power control, need efficient heat dissipation design due to their handling of high currents. Understanding the thermal conductivity of each component is crucial for heat dissipation design. The properties of power devices themselves (such as silicon, silicon carbide, gallium nitride, diamond, etc.) and heat dissipation materials (such as alumina, aluminum nitride, glass epoxy, various TIMs, copper, aluminum, encapsulants, die attach materials, etc.) are also important. There are so many materials to list.
This time, let's examine the thermal conductivity of silicon carbide and silicon.
Measurement Example: Thermal Conductivity of Silicon Carbide (SiC)
For about 10 years, our company has received requests to measure SiC, but recently it has become more common and is being used in various fields. Especially with the trend towards decarbonization, as various products are being electrified and made more efficient, its usage frequency is increasing. The thermal conductivity is approximately 100-350 [W/m·K]. As a power device semiconductor, it is currently attracting a lot of expectations and attention. Because it can be used at higher temperatures than silicon, measuring its thermal conductivity at high temperatures is also necessary.
The measurement example introduced this time is 6H-SiC. When measured with our Thermowave Analyzer TA33/35, the thermal conductivity (average measurement value of samples independently obtained by our company) is approximately 350 W/mK.
*Thermal conductivity is calculated from the measured value of thermal diffusivity, specific heat, and density from literature.
*Thermal conductivity is calculated from the measured value of thermal diffusivity, specific heat, and density from literature.
In addition, there are measurement examples of 4H-SiC, 6H-SiC with different crystal structures, and polycrystalline measured with a thermal microscope. Please refer to Case 3 in the catalog, which can be downloaded from the bottom of the page at this link.
Measurement Example: Differences in Thermal Conductivity of Five Types of Silicon Wafers
On the other hand, in general-purpose applications, silicon wafers, which are still indispensable for power semiconductors, are introduced in our measurement examples. We introduce the measurements of five types of silicon wafers obtained by our company.
The five types measured are as follows, differing in p-type/n-type and doping levels:
1. Silicon <0.02Ωcm / P, Low, 100
2. Silicon >1000Ωcm / P, High, 111
3. Silicon <0.02Ωcm / N, Low, 100
4. Silicon <0.02Ωcm / N, Low, 111
5. Silicon >1000Ωcm / N, High, 111
When measured with our Thermowave Analyzer TA33/35, the thermal conductivity (thermal diffusivity) results are:
1. Silicon <0.02Ωcm / P, Low, 100: approx. 120 W/mK (74 mm²/s)
2. Silicon >1000Ωcm / P, High, 111: approx. 140 W/mK (87 mm²/s)
3. Silicon <0.02Ωcm / N, Low, 100: approx. 120 W/mK (76 mm²/s)
4. Silicon <0.02Ωcm / N, Low, 111: approx. 120 W/mK (75 mm²/s)
5. Silicon >1000Ωcm / N, High, 111: approx. 140 W/mK (87 mm²/s)
*Thermal conductivity is calculated from the measured value of thermal diffusivity, specific heat, and density from literature.
*Thermal conductivity is calculated from the measured value of thermal diffusivity, specific heat, and density from literature.
As for thermal conductivity, there seems to be no significant difference between p-type and n-type. There appears to be a difference between high and low types.
Our Thermowave Analyzer TA33/35 can measure materials with low to high thermal conductivity, even materials with anisotropy, on the same workpiece, and is equipped with a mapping function.
For measurement requests, please contact Betel Corporation via the inquiry form.
For measurement requests, please contact Betel Corporation via the inquiry form.
This article is a re-edited version of the following articles ( in Japanese ):
