Difference between thermal grease and thermal gel

09 / 12 / 2021

Difference between thermal grease and thermal gel
Thermally conductive silicone gel and thermally conductive silicone grease are both thermal interface materials (TIM).

Thermal gel is a new thermal interface material that has emerged in recent years. However, thermal grease is the veteran of the thermally conductive interface material family.
Both thermal interface materials are in paste form, many customers have always been unclear about the difference between thermal gel and thermal grease. Some people even acquiesce that thermally conductive silicone gel is thermally conductive silicone grease, which is just a different name. Because of this, I will discuss the difference between thermal gel and thermal grease with everyone today.

What is thermal gel?
Thermally conductive gel is a very high-viscosity thermally conductive material, which is made by mixing a variety of thermally conductive powders and thermally conductive silica gel after being fully cured. The entire production process is completed in a vacuum state, so there is no air in the thermally conductive gel material. Most of the thermal gel packaging is in syringe.
Thermally conductive gel series have one part and two part as picture below, which are used for heat conduction and heat dissipation to help the laptop's chips to dissipate heat, such as CPU or GPU, etc.
We talked about thermal gel in details before. Go to check Understanding Thermal Gel

What is thermal grease?
Thermal grease is a kind of material used to fill the gap between the CPU and the heat sink. This material is also called thermal paste, thermal compound, thermal goop, thermal putty, heat sink compound and GPU thermal paste etc. Its function is to transfer the heat from the CPU to the heat sink, keep the CPU temperature at a stable working level, prevent the CPU from being damaged due to poor heat dissipation, and prolong its service life.
In the application of heat dissipation and heat conduction, even two flat surfaces with very smooth surfaces will have gaps when they are in contact with each other. The air in these gaps is a poor conductor of heat and will hinder the conduction of heat to the heat sink. The thermal grease is a material that can fill these gaps and make the heat conduction more smoothly and quickly.

There are many types of silicone grease on the market, and different parameters and physical properties determine different uses. For example, some are suitable for CPU heat conduction, some are suitable for memory heat conduction, and some are suitable for power heat conduction.
Thermally conductive putty is a kind of high thermal conductivity insulating silicone material, which almost never cures, and can maintain the state of grease when used for a long time at a temperature of -40°C to +200°C. It not only has excellent electrical insulation, but also excellent thermal conductivity, and at the same time has low oil separation (towards zero), high and low temperature resistance, water resistance, ozone resistance, and weathering resistance.
Heatsink paste can be widely applied to the contact surface between the heating element (power tube, thyristor, electric heating pile, etc.) and heat dissipation facilities (heat sink, heat sink, shell, etc.) in various electronic products and electrical equipment. The role of heat transfer medium and the performance of moisture-proof, dust-proof, anti-corrosion, and shock-proof.
It is suitable for surface coating or overall potting of various microwave devices such as microwave communications, microwave transmission equipment, microwave special power supplies, and stabilized power supplies. This type of silicon material provides excellent thermal conductivity for electronic components that generate heat. Such as: transistors, CPU assembly, thermistors, temperature sensors, automotive electronic parts, automotive refrigerators, power modules, printer heads, etc.

Differences between thermal grease and thermal gel
Thermal gel has an advantage over thermal grease:
Thermal conductive gel does not cause silicone oil to precipitate, and the gel can be peeled off and reused. When the thermal conductive gel is connected to the heat sink and the chip, only a small working pressure is required, generally less than 10psi, low hardness, easy to bend, and has a wide working temperature zone.
  • Material:
Electrically conductive grease is made of organic silicone as the main raw material, adding materials with excellent heat resistance and thermal conductivity to make a thermal conductive silicone grease-like compound
Thermal gel: It is a high-end thermal conductive compound.
  • Different characteristics
Thermal grease has high thermal conductivity, excellent thermal conductivity, good electrical insulation (only for insulating and thermally conductive silicone grease), wide use temperature, good use stability, low consistency and good construction performance.
Thermal gel: through the condensation reaction of moisture in the air, low molecules are released to cause cross-linking and curing, and then vulcanized into a high-performance elastomer. Has excellent resistance to cold and heat alternating performance, aging resistance and electrical insulation properties. And has excellent moisture resistance, shock resistance, corona resistance, leakage resistance and chemical resistance.
  • Different uses
Thermal paste is used for gap filling and heat transfer between high-power transistors, switch tubes, integrated circuits and other chips and heat sinks, such as power amplifiers, transistors, electronic tubes, CPUs, etc.
Thermal compound has excellent thermal conductivity, high temperature resistance, anti-aging, waterproof, insulation and other characteristics. It is insoluble in water, not easy to be oxidized, and has excellent electrical insulation properties so it can protect the circuit while conducting heat and improves the stability of the circuit. Thermal grease is currently the most widely used thermally conductive material in the electronic and electrical industry.

Thermal gel is widely used in the fields of LED chips, communication equipment, mobile phone CPUs, memory modules, IGBTs and other power modules, and power semiconductors
Different construction methods
  • Different construction methods
The construction method of thermal gel is better than thermal grease
The thermal grease is different from the thermal gel in terms of the formula or the production process of the thermal grease itself. The packaging method including the thermal grease is also simple canned.
The conventional construction method of thermal grease is screen printing, and some customers just apply and scrape evenly. But such a simple construction method must also be operated manually.

The thermal gel construction can be done directly by the automatic dispenser, which ends the history that thermal interface materials cannot be automated.
In this way the thermal conductive gel is in good contact with electronic products during assembly, showing low contact thermal resistance and good electrical insulation characteristics.

Simply put, thermal gel can be constructed with a fully automatic dispensing process, while the thermal grease can only be constructed manually.
  • Different working life
The working life of thermal gel is longer than thermal grease
The thermal gel does not dry for a long time and can be compressed indefinitely. It can guarantee a service life of more than 10 years. Some manufacturers call thermal gel a liquid thermal silica sheet.
But the life span of thermal conductive silicone grease (heat conductive putty) is shorter than that of all thermal interface materials. After half a year of use, the thermal conductive silicone grease begins to dry up slowly, and it can be completely turned into powder within 2 years. It becomes dust when you pinch it, and the thermal conductive silicone grease also loses its thermal conductivity. It is the end of the life of the thermal grease. This is also the case that thermal conductive silicone grease is often complained about, and it is also a fatal bottleneck in the development of thermal conductive silicone grease.

There are many differences between thermal gel and thermal grease, such as thermal resistance, thickness and so on. Therefore, this kind of evidence shows that thermal gel is not thermal grease, and both have their own uses. Customers can choose to use thermal gel or thermal grease or other thermal conductive materials according to the product characteristics and structure requirements.