Although thermally conductive graphite flakes are becoming more and more widely used in various industries, it is facing more and more challenges. As electronic products become smaller and smaller, the chip size becomes smaller and smaller, making thermal conduction difficult. What is the graphite sheet cut with?

Thermally conductive graphite flakes not only need to improve the thermal conductivity to meet the higher thermal conductivity requirements, but also need to continuously improve the size and process the site smaller and smaller. Whether the size meets the standard requirements is related to the cutting process of the thermally conductive graphite sheet.

The cutting process of thermally conductive graphite sheet is related to its practical application. There are two kinds commonly used: adhesive film and backing film. Adhesive film cutting refers to the cutting of graphite sheet with multiple backing treatment on its surface so that the graphite sheet has a certain adhesion. This adhesive laser die-cut can make the thermal conductive graphite sheet better bonded to the circuit board, better heat dissipation of electronic products. Sometimes, the size of the insulation and heat dissipation material required for the circuit board does not match the size of the thermally conductive graphite sheet, so the graphite sheet set backing needs to be treated to make it more compatible with the electronic product.

Currently, the graphite sheet laser cutting machine laser die-cutting machine or precision laser cutting machine. Graphite sheet laser cutting machine adopts the principle of laser cutting, which can cut the heat-conducting graphite sheet quickly and effectively. Due to the more mature application of laser technology, this graphite sheet laser cutting machine can be stable and long-term processing operations. However, due to the influence of the heat-conducting graphite sheet's own structure, the product is brittle and its thickness cannot be cut too thin. Therefore, although the laser cutting machine can realize thin cutting technology, it also cannot immediately realize finer graphite sheet size. Experts need to improve the performance of graphite flakes first.

Factors affecting the thermal conductivity of graphite flakes

Thermally conductive graphite sheet is a product made of natural graphene with good thermal conductivity. Sound is the main form of thermal conductivity of graphene. When this form of thermal conductivity changes, its thermal conductivity will change. The thermal conductivity, size, temperature, thickness and dispersion of graphene are all affected according to the research that has been done on thermally conductive graphite flakes, as detailed below.

Thermally conductive graphite flakes provide a pathway for phonon propagation in the direction of the graphene flake layer. Less contact between the filler and polymer interface and low interfacial contact resistance reduce the phonon scattering function at the edge of the graphene sheet, which facilitates an effective thermal conductivity network. Therefore, the thermal conductivity parallel to the direction of graphene sheet layer is better than that perpendicular to the graphene sheet layer. Due to the different preparation processes, different sizes and thicknesses of thermally conductive graphite flakes are obtained. Large graphite with large specific surface area can reduce edge phonon scattering and facilitate thermal conductivity. The smaller the thickness of graphite flakes, the larger the specific surface area and the better the thermal conductivity. However, due to the limitations of the preparation process, currently only 0.1mm can not be done no matter how thin the thickness is.

When the thermally conductive graphite sheet conducts heat, the change in temperature will also affect the thermal conductivity. After several tests, it is found that the thermal conductivity of graphite at 655℃ increases with the temperature, which is a limit value when the temperature is lower than the temperature; when the temperature exceeds 655℃ the thermal conductivity of graphite decreases as the temperature increases. However, when the content of graphene in the thermally conductive graphite sheet increases, the decrease of thermal conductivity efficiency will slow down. People can choose different graphite flakes containing graphene according to the need of heat dissipation.

Thermal conductivity of graphene flakes

Thermally conductive graphite sheet is a very popular heat dissipation material widely used in electronic products. Graphite chemically becomes carbon element, with stable molecular structure and strong thermal conductivity, thermally conductive graphite sheet also has strong thermal conductivity and electrical conductivity. The thermal conductivity of graphite flakes on the market is 150-150,000, and according to people's test W/(m-K) the conductivity between them is much higher than that of other thermally conductive materials. The high conductivity of graphite is also used in the production of batteries, but its conductivity is not emphasized in thermally conductive products.

Thermally conductive graphite flakes also have the advantages of low thermal resistance, light weight, corrosion resistance, and radiation resistance. The thermal resistance of graphite sheet is 40% lower than that of metallic aluminum, 20% lower than that of metallic copper, and 20% lower than that of copper; the weight of graphite sheet is 25% lighter than that of metal and 75% lighter than that of metallic copper. Although the thermal conductivity of metal aluminum and copper sheet is more than 20,000 W/(m-K), which is much higher than graphite, the above two points have poor performance and are not as suitable as graphite for thermal conductivity materials. When using thermally conductive graphite sheet in electronic products, there is no need to worry about the weight of the electronic product or the corrosive substances of the electronic components that will affect its thermal conductivity.

Thermally conductive graphite flakes also have good compressibility, resilience and low stress creep rate, making them ideal for sealing materials. According to the heat dissipation needs of electronic products, graphite is made into different thicknesses and sizes of thermally conductive flakes, which can play a certain role in shockproofing electronic components on circuit boards and protecting them from thermal conductivity damage. Due to the characteristics of thermally conductive graphite sheet, it has become a mainstream thermally conductive product that contributes to the performance of electronic products.