The Difference Between Thermal Grease and Thermal Gel

Both thermal grease and thermal gel are thermal interface materials, presenting a paste-like consistency that often leads to confusion, with some even believing they differ only in name. In reality, significant distinctions exist between them. Thermal grease represents a traditional, commonly used category within thermal interface materials, whereas thermal gel is a newer material that has gained prominence in recent years. The following provides a detailed analysis of their differences.

Thermal gel is a high-viscosity thermal interface material manufactured by thoroughly blending multiple heat-transfer powders with thermally conductive silicone, processed under vacuum conditions. It contains no residual bubbles and is typically packaged in syringes. It exhibits minimal solidification, maintaining a paste-like consistency over extended periods within the temperature range of -40°C to +200°C. It offers excellent thermal conductivity and electrical insulation, with extremely low oil separation rates, high resistance to extreme temperatures, moisture, and ageing. It requires minimal pressure for application between heat sinks and chips, and is reusable.

Thermal grease, also known as thermal paste or heat-dissipating silicone, primarily fills gaps between chips (such as CPUs and GPUs) and heat sinks. It compensates for air pockets (poor thermal conductors) in contact surfaces, accelerates heat transfer, protects electronic components, and extends their lifespan. Widely used between heating elements and cooling devices in various electronic and electrical equipment, it adapts to different application requirements but exhibits ageing over time.

Five core distinctions exist between the two:

• Firstly, differing raw materials. Thermal grease utilises silicone as its base, supplemented with high-temperature resistant and highly thermally conductive additives; thermal gel represents a premium heat transfer medium with a more specialised formulation.
• Secondly, their characteristics differ: thermal grease offers high thermal conductivity, low paste consistency, and cost-effective application; thermal gel cures via a water-activated hydroxymethyl condensation reaction, providing superior resistance to thermal cycling, water ingress, and chemical exposure.
• Thirdly, their applications differ: thermal grease is primarily used for gap filling between components such as CPUs and power amplifier circuits and heat sinks; thermal gel is suited for scenarios including LED chips, mobile phone CPUs, and IGBT power modules.
• Fourthly, their application methods vary: thermal grease is typically supplied in bottles and requires manual spreading and levelling; thermal gel can be applied via automated dispensing equipment, offering higher efficiency and superior contact results.
• Fifthly, their service lives differ: thermal gel maintains its properties long-term, lasting over ten years; thermal grease gradually hardens after six months and becomes powdery within two years, losing its thermal conductivity.

In summary, thermal gel and thermal grease are distinct materials, each possessing unique advantages and suitable applications. Users should select the appropriate thermal interface material based on product characteristics and structural requirements.