As electronic devices become increasingly miniaturized and high-performance, heat dissipation becomes one of the key factors that determine product stability and life. As an efficient and convenient thermal interface material, thermal conductive silicone pads play an indispensable role in the field of electronic heat dissipation.
Thermal conductive silicone pads are a sheet-like soft material made of silicone rubber as a base material and added with high thermal conductivity fillers. It has good thermal conductivity, insulation, compressibility, and filling properties.
Core characteristics of thermal conductive silicone pads
Thermal conductivity: The most important parameter to measure the thermal conductivity of a material, in W/m·K. The higher the value, the better the thermal conductivity. The common range is from 1.0 W/m·K to 10+ W/m·K or even higher, and needs to be selected according to heat dissipation requirements.
Thickness: Directly affects filling capacity and compressibility. It needs to be selected according to the actual gap between the component and the heat sink. Common thickness ranges from 0.3mm to 10mm. Too thick or too thin may affect performance.
Hardness/compression rate: Usually expressed in Shore hardness (Shore OO or Shore A). The lower the hardness and the higher the compression rate, the easier it is to fill irregular surfaces and tiny gaps, and the lower the contact thermal resistance. However, structural support and long-term compression deformation must also be considered.
Insulation strength: The thermally conductive silicone pad itself is an excellent insulator, and the insulation strength is usually at the kV/mm level, which can effectively prevent short circuits between components and heat sinks.
Thermal resistance: The unit area thermal resistance (℃·in²/W or ℃·cm²/W) sometimes reflects the interface thermal conductivity in actual applications better than the thermal conductivity, because it combines the effects of the material thermal conductivity and contact thermal resistance. The lower the value, the better.
Breakdown voltage: The voltage value when the material is electrically broken down is an important indicator of insulation performance.
Flame retardant grade: Such as UL94 V-0, V-1, etc., which are crucial for applications with high safety requirements.
Operating temperature range: The silicone substrate usually has a wide operating temperature range (such as -40℃ to 220℃+), which must meet the requirements of the equipment working environment.
Dielectric constant/loss factor: For high-frequency circuit applications, these parameters will affect signal integrity.
Main application scenarios of thermal conductive silicone pads
Consumer electronics: CPU, GPU, battery cooling of smartphones/tablets; laptop motherboard chipset, graphics card cooling; game console chip cooling; LED TV backlight driver cooling.
Communication equipment: Routers, switches, base station equipment in the main control chip, power amplifier, power module cooling.
Automotive electronics: Battery management system, motor controller, on-board charger, DC-DC converter, LED headlight driver cooling of new energy vehicles (requires high temperature resistance, aging resistance, and high flame retardancy).
Industrial control: PLC, servo drive, inverter power devices, main control chip cooling.
Power supply equipment: Switching power supply, transformer, MOS tube, rectifier bridge cooling in adapter.
LED lighting: Thermal conductive filling between LED lamp beads and heat dissipation aluminum substrate.
How to choose thermal conductive silicone pads correctly?
Clarify the heat dissipation requirements:
What is the power (heat generation) of the heat source?
What is the maximum allowable operating temperature?
How much temperature difference needs to be reduced?
Measure the gap size: Accurately measure the installation gap between the surface of the heat source and the surface of the heat sink (taking into account tolerance and compression).
Determine key parameters:
Thermal conductivity: Select according to the heat dissipation requirements. 1.0-3.0 W/m·K for general applications, 3.0-6.0 W/m·K for mid-to-high-end applications, and 6.0 W/m·K or more may be required for high power density or harsh environments.
Thickness: Select a thickness slightly larger than the actual gap (usually 10%-20% more) to ensure effective compression filling. Too thick will increase thermal resistance, and too thin will not fill the gap.
Hardness/compression rate: For good surface flatness, a slightly harder gasket can be selected; for uneven surfaces or height differences, a low hardness, high compressibility gasket should be selected.
Insulation/voltage resistance: Select a gasket that meets the insulation strength requirements according to the circuit voltage.
Flame retardant grade: Select according to industry or product safety standards (such as UL94 V-0).
Operating temperature range: Ensure that the maximum and minimum operating temperature requirements of the equipment are met.
Size and shape: Cut or custom die-cut according to the shape of the heat source.
Consider long-term reliability: Pay attention to the material's anti-aging performance, low stress relaxation (not easy to permanently deform after compression), chemical resistance, etc.
Cost factors: Consider cost-effectiveness while meeting performance requirements. The higher the thermal conductivity and the more special performance requirements, the higher the cost.
Precautions for using thermal conductive silicone pads
Surface cleaning: Be sure to clean the contact surface between the heat source and the radiator before use, remove oil, dust, and oxide layer to ensure good contact.
Tear off the protective film: The double-sided release film must be torn off before use.
Correct placement and pressure: Align the position and place it evenly to compress it fully. Avoid repeated tearing and pasting, which affects the viscosity and filling effect.
Avoid excessive compression: Excessive compression may cause the gasket to crack, permanently deform, or increase thermal resistance. Operate according to the recommended compression rate.
Storage conditions: Store in a cool and dry place, avoid high temperature, humidity, and direct sunlight.
