What parameter indicators should be paid attention to when using thermal conductive materials

Electronic components and circuits in electronic products inevitably generate heat during system operation. Heat not only leads to the waste of electrical energy, but also has a significant impact on the performance and lifespan of electronic components. By using corresponding system design and control methods to reduce the amount of heat generated, the heat can only be quickly dissipated, thereby reducing the problems of reduced device performance and shortened lifespan caused by heat generation. The main ways of heat dissipation are heat conduction, heat radiation, and heat convection.

The main heat sources in electronic systems include power supply, main controller (CPU, GPU, MPU), and power drivers (MOSFET, IGBT, etc.). In thermal management design, it is often necessary to consider the issue of thermal conduction between heating devices and heat sinks. Reasonable selection of heat transfer media should not only consider their heat transfer capacity, but also take into account various aspects such as production processes, installation and operation convenience, maintainability, and suitable cost-effectiveness. Advanced Institute will provide a detailed introduction to the parameters and indicators that need to be considered when selecting thermal conductive materials.

THERMAL GREASE

THERMAL GREASEIt is a high thermal conductivity insulating silicone material that can maintain a grease like state for a long time in the temperature range of -50 degrees to 230 degrees. Widely coated on the surface of various electronic products, the contact surface between heating elements (power tubes, thyristors, electric stacks, etc.) in electrical equipment and heat dissipation facilities (heat sinks, heat strips, shells, etc.) plays a role in heat transfer.

1. Is there silicone oil in the composition. Silicone oil has excellent thermal oxidation stability and electrical insulation properties, but it also has high gas solubility (with some volatility), high thermal expansion coefficient, and certain moisture absorption. Moreover, different types of silicone oil have a significant impact on the wettability and thermal resistance of thermal grease, and in certain situations, thermal grease without silicone oil is required.

2. Thermal conductivity. Thermal conductivity refers to the amount of heat transferred through an area of 1 square meter under stable heat transfer conditions, with a temperature difference of 1 degree (K, ℃) on both sides of a 1-meter-thick material, in watts per meter per degree (W/(m • K), where K can be replaced by ℃) within 1 second (1S). The larger the value, the better the thermal conductivity.

3. Thermal resistance coefficient. When heat is transferred through thermal conduction inside an object, the resistance encountered is called thermal resistance. When heat flows through the interface between two contacting solids, the interface itself exhibits a significant thermal resistance to heat flow. Therefore, it is necessary to minimize the gap between the thermal grease and the chip under a certain pressure. The smaller the parameter, the better.

4. Viscosity. A performance index used to characterize the flowability and viscosity of thermal conductive silicone grease, which is greatly affected by temperature.

5. Working temperature range. Due to the characteristics of silicone grease itself, its working temperature range is very wide. The working temperature is an important parameter to ensure that the thermal conductive silicone grease is in a solid or liquid state. If the temperature is too high, the volume of the thermal conductive silicone grease fluid expands, the distance between molecules increases, the interaction weakens, and the viscosity decreases; Low temperature, reduced fluid volume, shortened intermolecular distance, strengthened interactions, and increased viscosity are both unfavorable for heat dissipation.

In addition, it is necessary to consider the volume resistivity coefficient, which is an indicator of insulation performance. Some also require RoHS environmental certification to ensure non-toxic safety. Finally, it is necessary to consider whether it needs to be packaged in barrels, cans, or syringes based on the amount used.

Tensile strength generally refers to the critical value at which plastics or metals transition from uniform plastic deformation to locally concentrated plastic deformation, and is also the maximum bearing capacity of plastics or metals under static tensile conditions. For plastic materials, it characterizes the resistance to the maximum uniform plastic deformation of the material. Before the tensile specimen is subjected to the maximum tensile stress, the deformation is uniform and consistent, but after exceeding it, the metal begins to exhibit necking phenomenon, that is, concentrated deformation occurs; For brittle materials without (or with very little) uniform plastic deformation, it reflects the fracture resistance of the material.

Thermal conductive silicone sheet

Thermal conductive silicone sheetIt is a thick thermal pad specially designed for the use of gaps to transfer heat. It can fill gaps, complete the heat transfer between the heating and cooling parts, and also play a role in shock absorption, insulation, sealing, etc. It can meet the design requirements of miniaturization and ultra-thin equipment. When choosing a thermal conductive silicone sheet, in addition to paying attention to parameters such as thickness, thermal conductivity, thermal resistance, volume resistivity, dielectric constant, operating temperature range, and pressure resistance, it is also necessary to pay attention to parameters including hardness and tensile strength

Hardness is an important performance indicator for measuring the softness and hardness of metal materials. It can be understood as the ability of materials to resist elastic deformation, plastic deformation, or failure, or expressed as the ability of materials to resist residual deformation and anti failure. Hardness is not a simple physical concept, but a comprehensive indicator of mechanical properties such as elasticity, plasticity, strength, and toughness of materials.