Thermally conductive silica gel sheet is a kind of thermally conductive media material synthesized by a special process with silica gel as the base material and various auxiliary materials such as metal oxides.
Thermally conductive silicone rubber is a polymer composite material that uses silicone resin as the bonding material and is filled with thermally conductive powder to achieve the purpose of heat conduction.
Thermally conductive silicone can be divided into thermally conductive silicone gaskets and non-silicone silicone gaskets.
The electrical insulation properties of most thermally conductive silica gels are ultimately determined by the insulation properties of the filler particles.
Thermally conductive silicone gasket
Thermally conductive silicone gaskets are divided into many sub-categories, each with its own different characteristics.
Non-silicone silicone gasket
Non-silicone silicone gasket is a material with high thermal conductivity. It is self-adhesive on both sides.
When used in the assembly of electronic components, it exhibits lower thermal resistance and better electrical insulation characteristics under low compression force. It can work stably at -40℃~150℃. Meet the flame retardant grade requirements of UL94V0.
Thermal conductive silicone gasket double-sided adhesive.
The double-sided adhesive is mainly because the product has no fixing device or is inconvenient to fix.
The double-sided adhesive can be used to fix the radiator, stick the IC and the heat sink, and there is no need to design a fixing structure.
Benefits: It can be used to fix the radiator, without the need to design a fixed structure.
Impact: The thermal conductivity will be worse, and the derivative coefficient will be much lower.
Single-sided adhesive for thermal conductive silicone gasket
The single-sided adhesive is mainly to facilitate the installation and bonding of thermal silica.
For example, a backlight source uses thermal silica with a size of 400*6, which is not easy to install.
Therefore, the single-sided adhesive should be used, and the thermal silica is glued. One side is attached to the PCB board, and the other side is attached to the housing.
Benefit: It can stick to the surface of the heater on one side.
When the radiator or the shell slides relatively during the assembly process, the thermally conductive silicone gasket will not cause a position shift.
Impact: The thermal conductivity will be lower, but the effect is better than double-sided adhesive.
To sum up, whether it is a double-sided adhesive or a single-sided adhesive for thermally conductive silicone gaskets will result in lower thermal conductivity, but it is conducive to structural design and installation.
Thermal conductivity selection. The choice of thermal conductivity mainly depends on the power consumption of the heat source and the heat dissipation capacity of the radiator or heat dissipation structure.
Generally, the chip temperature specifications are relatively low, or sensitive to temperature, or heat flux density is relatively large (generally greater than 0.6w/cm3 requires heat dissipation treatment, generally when the surface is less than 0.04w/cm2, only natural convection treatment is required) these chips Or the heat source needs to be heat-dissipated, and try to choose a thermally conductive silicone sheet with high thermal conductivity.
The consumer electronics industry generally does not allow the junction temperature of the chip to be higher than 85 degrees, and it is also recommended to control the chip surface to be less than 75 degrees during the high-temperature test. The components of the entire board are basically commercial-grade components, so the internal temperature of the system is recommended at room temperature.No more than 50 degrees.
It is recommended that the temperature of the first appearance surface, or the surface that can be contacted by the end customer, be lower than 45 degrees at room temperature. Choosing a thermally conductive silicone sheet with higher thermal conductivity can meet the design requirements and retain some design margins.