What is thermal paste?
Thermally conductive cement, commonly known as thermally conductive gel or thermally conductive mud, is a gel-like thermally conductive material made of silica gel composite thermally conductive fillers after stirring, mixing and packaging. This material has some advantages of thermal pad and thermal grease at the same time, and better makes up for the weaknesses of both.
Thermally conductive cement inherits the advantages of good affinity, weather resistance, high and low temperature resistance, and good insulation of silicone materials. At the same time, it has strong plasticity and can meet the filling of uneven interfaces, and can meet the heat transfer requirements in various applications.
Introduction to the classification of thermal paste
Thermally conductive cement can be divided into two products in the industry: one is thermally conductive cement; the other is thermally conductive cement gasket, also known as thermally conductive gel gasket or thermally conductive cement gasket. There is a big difference in method.
Thermal paste is divided into one-component thermal paste and two-component thermal paste. One-component thermal conductive cement is a high-performance thermal conductive gel. It is made of silica gel and filled with a variety of high-performance ceramic powders. The thermal conductive gel has high thermal conductivity, low thermal resistance, and is suitable for heat dissipation Good insulation, can automatically fill the gap, maximize the limited contact area, and can be infinitely compressed.
Two-component thermal conductive cement is a filling material that can be filled in the thermal gap in liquid form. After mixing the two liquids in a 1:1 ratio, they can react at room temperature (or accelerate the reaction by heating), and become an ultra-soft thermal conductive filling material. The reaction process of the two-component thermal conductive cement No by-products, it can be deep-cured, and the cured product has high compressibility and cushioning properties.
The thermally conductive glue gasket is a highly integrated ultra-soft thermally conductive silicone sheet. The thermally conductive glued gasket product preserves the high-quality thermal conductivity of the thermally conductive silicone sheet material, and is easy to adapt to and adhere to parts with uneven surfaces to achieve reliable and complete performance. physical contact.
Introduction to the characteristics of thermal paste
Compared with the thermal pad, the thermal paste is softer and has better surface affinity. It can be compressed to a very low thickness, which can significantly improve the heat transfer efficiency. The minimum can be compressed to 0.1mm, and the thermal resistance at this time can be 0.08 ℃·in2/W – 0.3 ℃·in2/W, can reach the performance of some silicone grease.
In addition, the thermal conductive cement has almost no hardness, and will not cause internal stress to the equipment after use.
Compared with thermal grease, thermal paste is easier to operate. The general use of silicone grease is screen or steel plate printing, or direct brushing, which is very unfriendly to users and the environment, and because of its fluidity, it is generally not used for occasions with a thickness of more than 0.2mm.
The thermally conductive paste can be arbitrarily formed into the desired shape, which can ensure good contact for uneven PCB boards and irregular devices (such as batteries, component corners, etc.).
Thermal paste has a certain adhesion, and there is no problem of oil out and drying out, and it has certain advantages in reliability.
Advantages of continuous operation
The thermal conductive cement can be directly weighed and used. The commonly used continuous use method is the glue dispenser, which can realize fixed-point quantitative control, save labor and improve production efficiency.
Introduction to the application fields of thermal paste
Thermal paste is widely used in LED chips, drones, communication equipment, mobile phone CPUs, memory modules, IGBTs and other power modules, and power semiconductors.
The application of thermal conductive cement in driving power supply in LED bulb lamp. In the export of LED lamps, in order to pass the UL certification, manufacturers mostly use two-component potting glue for potting. Lamps exported to the United States all require a 50,000-hour warranty. At present, the quality of the LED lamp beads is no problem. The main fault is the power supply. The power supply after potting with potting glue cannot be disassembled. Lamps are scrapped and replaced. If the power supply is partially filled with thermally conductive cement, the heat can be effectively dissipated. If there is a problem with the power supply, the power supply can be easily replaced, which saves costs for the enterprise. Of course, for lamps that require waterproofing, because the thermally conductive cement cannot fill all the gaps and gaps like potting glue, and cannot be waterproof and moisture-proof, potting glue is still required.
Another typical application is in the LED fluorescent tube. For the design of the power supply at both ends, in order not to occupy too much the size of the tube, the space for the power supply at both ends is relatively small, and the power of the 1.2-meter LED fluorescent lamp is usually designed to 18w. To 20w, the calorific value of the driving power becomes relatively large. The thermal paste can be filled into the gap of the power supply, especially attached to the power device to help dissipate heat and prolong the life of the lamp. For some sealed module power supplies, it can be partially filled with thermal paste to achieve thermal conductivity.
Then there is the heat dissipation of the chip. Everyone should be familiar with this method. The silicone grease layer between the similar processor and the heat sink is a principle. Its function is to allow the heat emitted by the processor to be transmitted faster. to the radiator to dissipate.
Similarly, thermal paste can also be applied to mobile phone processors. On the processors of Huawei mobile phones, thermal paste heat dissipation glue similar to silicone grease is used, which has better contact effect than the graphite heat dissipation film only, and the heat conduction is better. will be faster.