Views: 22 Author: Site Editor Publish Time: 2024-12-10 Origin: Site
Thermal grease, also known as thermal compound, is a widely used thermal interface material. It is a paste-like substance made primarily from silicone oil (organosilicone) combined with thickeners and fillers, processed through heating, degassing, and grinding. The resulting compound is viscous and free of noticeable particles, capable of filling various microgaps. The color of the grease varies depending on the added thermal conductive materials.
The main thermal conductive materials include graphite powder, aluminum oxide, aluminum nitride powder, and copper powder. High-end products may incorporate silver. Most of the metallic components are metal composites, offering high insulation properties, with very few products containing pure metal powder.
1. Liquid form with excellent wetting properties.
2. High thermal conductivity, heat resistance, aging resistance, and waterproof properties.
3. Insoluble in water and resistant to oxidation.
4. Provides lubrication and electrical insulation.
5. Cost-effective.
Thermal conductivity measures the heat transfer efficiency of a material. It is expressed in W/(m·K), indicating the power of heat transfer through a material with a 1-meter thickness and a 1°C (or 1K) temperature difference. Higher values indicate faster heat transfer and better thermal performance. This is a critical parameter for evaluating the efficiency of thermal grease.
Although rarely used today, this parameter represents the heat transferred through 1 square meter of material per hour under a 1°C (or 1K) temperature difference. It differs from thermal conductivity and is used in only a few products. If this parameter is provided, a higher value indicates better performance.
Thermal impedance quantifies a material's resistance to heat flow, expressed in ℃/W. It measures the temperature difference between two ends of a material when transferring 1 watt of heat. Lower thermal impedance is preferable, as it results in lower operating temperatures under the same thermal load. Most modern thermal greases have a thermal impedance below 0.01℃/W, with premium options reaching below 0.005℃/W.
Viscosity reflects the internal resistance of the fluid to flow. High viscosity makes the grease behave like glue, aiding in adherence but potentially complicating application. Low viscosity, on the other hand, allows easy spreading but can result in the material flowing uncontrollably.
Thermal grease typically operates between -50℃ to +180℃. Higher-end products can extend this range to -250℃ to +300℃. For most applications, this range suffices to maintain optimal performance.
The dielectric constant measures a material's ability to store electrical energy relative to a vacuum. Most thermal greases are highly insulating, with a dielectric constant around 5, while air has a value of approximately 1. Special thermal greases containing silver may exhibit slight conductivity. This parameter is rarely specified, as most products maintain excellent insulation.
Oil separation refers to the tendency of silicone oil to separate from the compound over time, especially under high temperatures. It is measured by the amount of silicone oil released after 24 hours at 200℃. High oil separation can lead to contamination of components, while low separation ensures stable performance. Silicone oil is essential for easy application and effective filling of micro-textures, balancing thermal efficiency and ease of use.
1. Ensure the grease does not solidify during use, as this degrades thermal performance.
2. Opt for low oil separation to prevent contamination of components.
3. Choose low-volatility products to avoid pollution and degradation over time.
4. Check for high insulation and temperature resistance, ensuring the grease can withstand the intended operating environment.
