I. Thermal Conductivity (Thermal Conductivity)
Thermal conductivity is a key indicator for evaluating the heat-conducting ability of thermal conductive silicone sheets. The higher the thermal conductivity, the better the heat-conducting performance of the material. In practical applications, it is usually desired that the thermal conductive silicone sheets have a high thermal conductivity to effectively reduce the operating temperature of electronic devices. The unit of thermal conductivity is W/m.K, and the common thermal conductivity of thermal conductive silicone sheets ranges from 1.0 W/m.K to 10.0 W/m.K. The specific choice depends on the actual requirements.
The determination of thermal conductivity is usually carried out using laser thermal conductivity methods or hot wire methods. The former heats the material surface with laser pulses and measures the temperature response; the latter heats the probe with a constant power and measures the temperature increase. Regardless of which method is used, accurately measuring the thermal conductivity is crucial for evaluating the performance of the material.
II. Hardness (Hardness)
Hardness is one of the important physical performance indicators of thermal conductive silicone sheets, directly affecting their application scenarios and installation convenience. Hardness is generally measured using a Shore hardness tester, with a common range of 20 Shore C to 60 Shore C. Materials with too high hardness may exert pressure on electronic components during installation, even damaging the components; while materials with too low hardness may not provide sufficient mechanical support.
In practical applications, an appropriate hardness of thermal conductive silicone sheets needs to be selected based on the specific application environment and requirements. For example, in applications requiring strong support, materials with higher hardness are suitable; in applications requiring better adhesion, materials with lower hardness should be selected to ensure good contact and heat-conducting performance.
III. Thickness (Thickness)
Thickness is also an important factor affecting the performance of thermal conductive silicone sheets. Different thicknesses of thermal conductive silicone sheets are suitable for different application scenarios. Generally, the thinner the thickness, the better the heat dissipation effect, as the thermal resistance is smaller, but it may also be difficult to fill large gaps; the thicker the thickness, the better the filling performance, but it may lead to an increase in thermal resistance.
The selection of thickness needs to be comprehensively considered based on the structural design of the equipment, the gap between components, and the thermal management requirements. The thickness range of thermal conductive silicone sheets is usually between 0.5 mm and 20 mm, and the specific choice should be adjusted based on the actual application requirements.
IV. Temperature Resistance (Temperature Resistance)
Temperature resistance is an important performance indicator of thermal conductive silicone sheets, determining the stability and reliability of the material in high-temperature environments. Thermal conductive silicone sheets usually need to maintain good heat-conducting performance and mechanical properties in a wide temperature range. Common thermal resistance ranges for thermal conductive silicone sheets are -40℃ to 200℃, and some special applications may require higher temperature resistance.
The determination of temperature resistance is usually carried out using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA is used to measure the mass change of the material at different temperatures to evaluate its thermal stability; DSC is used to measure the heat flow change of the material at different temperatures to evaluate its thermal properties.
V. Breakdown Voltage (Breakdown Voltage)
Breakdown voltage is an important indicator for evaluating the electrical insulation performance of thermal conductive silicone sheets, especially in applications requiring electrical isolation. The higher the breakdown voltage, the better the electrical insulation performance of the material. Generally, the breakdown voltage range of thermal conductive silicone sheets is 4 kV/mm to 20 kV/mm.
The measurement of breakdown voltage is usually carried out using high-voltage testing equipment, recording the voltage value at which the material undergoes electrical breakdown as the voltage is gradually increased. This indicator is of great significance for ensuring the safe operation of electronic devices.
VI. Compression Deformation Rate
The compression deformation rate refers to the degree of deformation of the heat dissipation silicone sheet under the action of pressure. This indicator affects the adhesion performance and service life of the material. Materials with excessively high compression deformation rates may lose their elasticity over time, thereby affecting the heat dissipation effect; materials with excessively low compression deformation rates may fail to effectively fill the gaps under the pressure.
The compression deformation rate is usually determined through compression tests, measuring the thickness change of the material under certain pressure and temperature conditions. The common range of compression deformation rates is between 5% and 30%, and the specific selection should be adjusted according to the application requirements.
VII. Aging Resistance
Aging resistance refers to the degree of performance change of the heat dissipation silicone sheet during long-term use. Excellent aging resistance ensures that the material maintains stable thermal conductivity and mechanical properties during long-term use. The evaluation of aging resistance is usually conducted through accelerated aging tests, measuring the performance changes of the material under high temperature and high humidity conditions.
The quality of aging resistance directly affects the service life and reliability of the heat dissipation silicone sheet, and is one of the factors that need to be carefully considered when selecting the material.
VIII. Flame Retardancy
Flame retardancy is an important safety performance indicator for heat dissipation silicone sheets in high-temperature or fire environments. Materials with good flame retardancy can effectively prevent the spread of flames and improve the safety of equipment. The determination of flame retardancy is usually carried out according to the UL 94 standard, with common grades including V-0, V-1, and V-2.
The improvement of flame retardancy is usually achieved by adding flame retardants, but it is necessary to note that flame retardants may affect the thermal conductivity and mechanical properties of the material, so a comprehensive consideration is required in practical applications.
IX. Volume Resistivity
Volume resistivity is another important indicator for measuring the electrical insulation performance of heat dissipation silicone sheets. The higher the volume resistivity, the better the electrical insulation performance of the material. It is particularly important in applications where current leakage needs to be prevented. The common range of volume resistivity for heat dissipation silicone sheets is above 10^14 Ω·cm.
The measurement of volume resistivity is usually carried out using a resistivity testing device, recording the resistance value of the material under a certain voltage. High volume resistivity can effectively prevent electrical faults and ensure the safe operation of electronic equipment.
The heat dissipation silicone sheet, as an indispensable heat-conducting material in electronic devices, its performance indicators directly affect the heat dissipation effect and safety of the equipment. By deeply exploring the main indicators such as thermal conductivity, hardness, thickness, temperature resistance, breakdown voltage, compression deformation rate, aging resistance, flame retardancy, and volume resistivity, we can have a more comprehensive understanding and selection of heat dissipation silicone sheets suitable for different application requirements. In practical applications, it is necessary to consider various performance indicators comprehensively based on the specific equipment and usage environment, and select the best heat dissipation silicone sheet to ensure the stable operation and long lifespan of the equipment. With the continuous advancement of technology and the diversification of application needs, the performance requirements of heat dissipation silicone sheets are also constantly increasing. In the future, heat dissipation silicone sheets will develop towards higher thermal conductivity, better mechanical properties, stronger electrical insulation, and longer durability, providing more reliable solutions for the heat dissipation management of electronic devices.
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Written by
CoolingThermal Engineering TeamCoolingThermal is an automation equipment manufacturer based in Kunshan, China, specializing in heat pipe and vapor chamber production equipment since 2017. Our engineering team designs, builds, and commissions complete production lines covering forming, degassing, welding, testing, and assembly processes. The technical content on this blog is written by the same team that develops the equipment — based on real production experience, not secondary research.
