What is the core issue of the thermal conductivity problem

The main factors affecting the thermal conductivity of thermal insulation materials:

First, the type of material.

Depending on the type of insulation (insulation), the thermal conductivity is different. The material composition of thermal insulation materials is different, and their physical and thermal properties are also different; There are differences in the thermal insulation mechanism, and their thermal conductivity or thermal conductivity is also different.

Even for insulation materials made of the same substance, the thermal conductivity can vary greatly depending on the internal structure or the production control process. For solid insulation materials with low porosity, the thermal conductivity of the crystalline structure is the largest, followed by the microcrystalline structure, and the smallest of the glass structure. However, for thermal insulation materials with high porosity, because the influence of gas (air) on the thermal conductivity plays a major role, the solid part has little effect on the thermal conductivity, whether it is a crystalline structure or a glass structure.

Second, the working temperature.

Temperature has a direct impact on the thermal conductivity of various thermal insulation materials, and the thermal conductivity of materials increases when the temperature increases. As the temperature increases, the thermal movement of the solid molecules of the material increases, and at the same time, the thermal conductivity of the air in the pores of the material and the radiation between the pore walls also increase. However, this effect is not significant in the temperature range of 0-50, and the effect of temperature should only be considered for materials at high or negative temperatures.

Try to choose a thinner thermally conductive silica gel sheet under the conditions allowed by the product design, because the thinner the thickness of the thermally conductive silica gel sheet with the same thermal conductivity, the cheaper, and the better the thermal conductivity effect (the thinner the thinner, the smaller the thermal resistance). Choosing a good thermally conductive silicone sheet for heat dissipation, coupled with the correct use method, can perfectly solve the problem of product heat dissipation.

The characteristics of thermal conductive agents are that they have a small thermal resistance to ordinary materials, soft and slightly extruded, which can completely fit 2 heat transfer surfaces, and the thickness can be very thin to reduce the impact on heat dissipation Thermal conductive agents are generally used on the bottom plate So by the way, it is also commonly used on CPUs Thermal grease, thermal lead pads, thermal conductive silicone, thermal rubber, thermal cement The more these materials are in front, the better the use effect But although these materials are much smaller than air, there is no low thermal resistance of copper and aluminum.

[Affect the conduction of thermal insulation materials.

The main factor of thermal coefficient].

1. Temperature: Temperature has a direct impact on the thermal conductivity of various thermal insulation materials, and the thermal conductivity of materials increases when the temperature increases.

2. Moisture content: All insulation materials have a porous structure and are easy to absorb moisture. When the moisture content is greater than 5% to 10%, the moisture of the material occupies part of the pore space originally filled with air after moisture absorption, causing its effective thermal conductivity to increase significantly.

3. Bulk density: bulk density is a direct reflection of the porosity of the material, because the thermal conductivity of the gas phase is usually smaller than that of the solid phase, so the insulation materials have a large porosity, that is, a small bulk density. In general, increasing the porosity or decreasing the bulk density will result in a decrease in the thermal conductivity.

4. Particle size of loose materials: At room temperature, the thermal conductivity of loose materials decreases with the decrease of material particle size, and when the particle size is large, the size of the void between particles increases, and the thermal conductivity of air inevitably increases. If the particle size is small, the temperature coefficient of the thermal conductivity is small.

5. Direction of heat flow: The relationship between thermal conductivity and direction of heat flow only exists in anisotropic materials, that is, in materials that are constructed differently in all directions. The adiabatic performance when the heat transfer direction is perpendicular to the fiber direction is better than that when the heat transfer direction is parallel to the fiber direction; Similarly, materials with a large number of closed pores are better insulated than those with large open pores.

The stomatous material is further divided into two types: solid matter, in which bubbles and solid particles are slightly in contact with each other. From the arrangement state, fibrous materials are divided into two situations: the direction is perpendicular to the heat flow direction and the fiber direction is parallel to the heat flow direction, under normal circumstances, the fiber arrangement of the fiber insulation material is the latter or close to the latter, and the thermal conductivity of the same density condition is much smaller than that of other forms of porous insulation materials.

6. The influence of filling gas: In thermal insulation materials, most of the heat is conducted from the gas in the pores. Therefore, the thermal conductivity of the insulation material is largely determined by the type of filling gas.

If helium or hydrogen is filled in cryogenic engineering, it can be used as a first-order approximation, and the thermal conductivity of the insulation material is considered to be comparable to the thermal conductivity of these gases, because the thermal conductivity of helium or hydrogen is relatively large.

7. Specific heat capacity: The specific heat capacity of the insulation material is related to the calculation of the cooling capacity (or heat) required by the insulation structure when cooling and heating. At low temperatures, the specific heat capacity of all solids varies greatly.

At room temperature and pressure, the mass of the air does not exceed 5% of the insulation, but as the temperature drops, the proportion of gas is increasing. Therefore, this factor should be taken into account when calculating insulation materials that work at atmospheric pressure.

8. Linear expansion coefficient: When calculating the firmness and stability of the adiabatic structure in the process of cooling (or heating), it is necessary to know the linear expansion coefficient of the insulating material. If the coefficient of linear expansion of the insulation material is smaller, the less likely it is that the insulation structure will be damaged by thermal expansion and contraction during use.

The linear expansion coefficient values of most insulation materials decrease significantly as the temperature decreases.

1. The thermally conductive material oxide itself. 2. The thickness of the coating when used after synthesis.

The core temperature will be higher, but not so much, it should be that the internal heat conduction of the CPU is not good.

The software itself is not very normal. To know this, you still have to go to the motherboard to check it. After all, it's about the drivers used by the software. The motherboard is a little bit worse than the direct use of hardware and the simulation of software... You can't count them all... It can only be said to be a reference.

Possibly, but it should be normal.

Hello landlord! glpoly's thermal management solutions experts around you have the answers:

Thermally conductive material is a new type of industrial material. These materials have been designed in recent years for the thermal conductivity requirements of equipment and provide excellent performance and reliability. They are suitable for a variety of environments and requirements, have proper countermeasures to possible thermal conductivity problems, provide a strong help for the high integration of equipment, and ultra-small and ultra-thin, the thermal conductivity products have been more and more used in many products, improving the reliability of the product.

The main types of thermal conductive materials commonly used in the market are: thermally conductive silica gel sheet, thermally conductive insulating sheet, thermally conductive double-sided tape, thermally conductive silicone grease, thermally conductive potting compound, thermally conductive phase change material, and thermally conductive gel.

The following types are described in a comprehensive manner, and the thermal conductive materials with the best thermal conductivity and reliability are preferred:

Laird, Parker Chomerics, Bergquist

The heat conduction of the material is mainly carried out by electrons and phonons, and photons are also involved at high temperatures.

1. The main thermal conductivity mechanism of pure metal is electronic thermal conduction, but the influence of phonons is also considered when the electrical conductivity is low and the temperature is low.

2. The main thermal conduction mechanism of ceramics is phonon heat conduction, and there is photon heat conduction at high temperature.

3. The main thermal conduction mechanism of polymer materials is the phonon heat conduction through the collision between molecules.

Starting from 22 nanometers, the top cover of the processor of the 115X interface and the CPU silicon wafer are coated with silicone grease, which is no longer the previous brazing, when the processor load is not high, it is basically no problem, and once the high load is running, because the thermal conductivity of the silicone grease is low, it is easy to have such a problem, that is, the silicon wafer has accumulated a lot of heat and cannot be conducted, so there is an operation, the CPU opens the cover, and re-applies the silicone grease with high thermal conductivity or the most common liquid metal after opening.