How to measure the thermal conductivity of the routing material in an IGBT heat sink?

As a supplier of IGBT Heat Sink Routing materials, understanding how to measure the thermal conductivity of our routing materials is crucial. Thermal conductivity is a fundamental property that determines how effectively a material can transfer heat. In the context of IGBT heat sinks, efficient heat transfer is essential for maintaining the optimal performance and longevity of the IGBT modules. In this blog post, I will explore various methods for measuring the thermal conductivity of routing materials in IGBT heat sinks.

Importance of Thermal Conductivity in IGBT Heat Sinks

IGBT (Insulated Gate Bipolar Transistor) modules are widely used in high - power electronic applications such as electric vehicles, renewable energy systems, and industrial motor drives. During operation, these modules generate a significant amount of heat. If this heat is not dissipated properly, the temperature of the IGBT module will rise, which can lead to reduced efficiency, decreased reliability, and even device failure.

The routing material in an IGBT heat sink plays a key role in heat transfer. A material with high thermal conductivity can quickly transfer the heat generated by the IGBT module to the heat sink fins, where it can be dissipated into the surrounding environment. Therefore, accurately measuring the thermal conductivity of the routing material is vital for selecting the right material and optimizing the design of the heat sink.

Methods for Measuring Thermal Conductivity

1. Steady - State Methods

a. Guarded Hot Plate Method

The guarded hot plate method is one of the most widely used steady - state methods for measuring thermal conductivity. In this method, a sample of the routing material is placed between two flat plates: a hot plate and a cold plate. The hot plate supplies a constant heat flux to the sample, and the cold plate absorbs the heat. A thermocouple is used to measure the temperature difference between the two plates.

The thermal conductivity (k) can be calculated using the following formula:
[k=\frac{Q\cdot L}{A\cdot\Delta T}]
where (Q) is the heat flux, (L) is the thickness of the sample, (A) is the cross - sectional area of the sample, and (\Delta T) is the temperature difference between the hot and cold plates.

The advantage of the guarded hot plate method is its high accuracy and reliability. It can measure the thermal conductivity of various types of materials, including solids, liquids, and gases. However, it is a relatively slow method, as it requires a long time to reach a steady - state condition.

b. Heat Flow Meter Method

The heat flow meter method is another steady - state method. It is similar to the guarded hot plate method, but instead of measuring the heat flux directly, it uses a heat flow meter to measure the heat transfer rate through the sample.

The heat flow meter consists of a thermopile that generates a voltage proportional to the heat flow. By measuring the voltage and the temperature difference across the sample, the thermal conductivity can be calculated.

The heat flow meter method is faster than the guarded hot plate method and is suitable for measuring the thermal conductivity of thin materials. However, it may have some limitations in accuracy, especially for materials with low thermal conductivity.

2. Transient Methods

a. Transient Plane Source (TPS) Method

The Transient Plane Source method is a popular transient method for measuring thermal conductivity. In this method, a thin, circular heating element is placed between two samples of the routing material. The heating element is used to generate a short - duration heat pulse, and the temperature response of the samples is measured as a function of time.

The thermal conductivity can be determined by analyzing the temperature - time curve using a mathematical model. The TPS method has several advantages, including fast measurement time, the ability to measure anisotropic materials, and a wide range of applicable thermal conductivity values.

b. Laser Flash Method

The laser flash method is commonly used to measure the thermal diffusivity of materials, which can then be used to calculate the thermal conductivity. In this method, a short laser pulse is applied to one side of the sample, and the temperature rise on the other side is measured using an infrared detector.

The thermal diffusivity ((\alpha)) is calculated from the time it takes for the temperature to reach a certain fraction of its maximum value. The thermal conductivity (k) can then be calculated using the following formula:
[k=\rho\cdot C_p\cdot\alpha]
where (\rho) is the density of the material and (C_p) is the specific heat capacity.

The laser flash method is suitable for high - thermal - conductivity materials and can provide accurate results in a relatively short time. However, it requires precise control of the experimental conditions and may not be suitable for materials with low thermal diffusivity.

Factors Affecting the Measurement of Thermal Conductivity

1. Temperature

Thermal conductivity is temperature - dependent. In general, the thermal conductivity of most materials decreases with increasing temperature. Therefore, it is important to measure the thermal conductivity at the operating temperature of the IGBT heat sink to ensure accurate results.

2. Sample Preparation

The quality of the sample preparation can significantly affect the measurement of thermal conductivity. The sample should have a uniform thickness, smooth surfaces, and no air gaps or impurities. Any non - uniformity or defects in the sample can introduce errors in the measurement.

3. Contact Resistance

Contact resistance between the sample and the measurement equipment can also affect the accuracy of the thermal conductivity measurement. To minimize contact resistance, suitable thermal interface materials can be used between the sample and the plates or sensors.

Product Recommendations

At our company, we offer a wide range of high - quality heat sinks, including the Five Star Silver Heat Sink 20W for COB Light, Copper Skiving Heat Exchanger Heat Pipe Cu Radiator Heat Sink, and Copper Extrusion Rectangle Extruded Heat Sink 1u. Our heat sinks are designed to provide excellent heat dissipation performance, and we ensure that the routing materials used in them have high thermal conductivity.

Conclusion

Accurately measuring the thermal conductivity of the routing material in an IGBT heat sink is essential for ensuring the efficient operation of IGBT modules. Both steady - state and transient methods can be used for this purpose, each with its own advantages and limitations. By considering factors such as temperature, sample preparation, and contact resistance, we can obtain more accurate measurement results.

If you are in the market for high - quality IGBT heat sink routing materials or heat sinks, we are here to help. We can provide you with detailed information about the thermal conductivity of our products and work with you to select the most suitable solutions for your applications. Contact us to start a discussion about your procurement needs.

References

• Zhang, X., & Chen, Y. (2018). Handbook of Thermal Conductivity. Elsevier.
• ASTM International. (2019). Standard Test Methods for Steady - State Heat Flux Measurements and Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus. ASTM C518.
• Maleki, M., & Haghdadi, A. (2015). Transient Methods for Measuring Thermal Properties. In Thermal Conductivity 42. Springer.