Key points and parameters for selecting thermal conductive silicone grease for LED lighting fixtures

In the thermal conductivity system of LED lighting fixtures, it mainly includes heating components, aluminum substrate heat sinks, LED aluminum substrate heat dissipation silicone grease, and air. The thermal conductivity of aluminum substrates includes ordinary thermal conductivity and high thermal conductivity. The general thermal conductivity of aluminum substrates is 1.0W/m.k-3.0W/m.k, of which 3.0W/m.k is considered high thermal conductivity. The thermal conductivity of thermal grease is about 0.8-6.0 W/m.k, while the thermal conductivity of air is only 0.02227W/m.k.

(Structure diagram of LED light)

The higher the thermal conductivity between the aluminum substrate and the heating element, the faster the heat dissipation speed. Therefore, the most perfect LED heat dissipation structure is the thermal element, aluminum substrate heat sink, and heat dissipation silicone grease. That is to say, the selection of thermal conductivity silicone grease for the aluminum substrate of LED bulb lamps is particularly important. So, we can mainly start from the following points:

1. Temperature resistance characteristics

Because LED generates a large amount of heat during operation, the surface temperature of the heating components may be very high, up to nearly 200 ℃. If the temperature resistance of the aluminum substrate heat dissipation silicone grease for LED lamps is lower than the surface temperature of the heating components, it will naturally be unable to dissipate heat normally. Generally, the temperature resistance of the heat dissipation silicone grease is sufficient at 200 ℃.

2. Rheological properties

Appropriate rheological properties are beneficial in ensuring that the gaps between the aluminum substrate and the heating components are filled with LED aluminum substrate heat dissipation silicone grease, ensuring full coverage and improving heat dissipation speed, thereby enhancing the performance and product lifespan of LED lighting fixtures.

3. Thermal conductivity coefficient

This mainly depends on the power of the LED lighting fixture, ultimately the highest heat dissipation during the operation of the fixture, combined with the heat dissipation contact surface, to calculate the required thermal conductivity of the silicone grease. If the thermal conductivity is chosen too low, it is easy to cause LED lamps to burn out; If the thermal conductivity of silicone grease is too high, it mainly leads to cost waste. Therefore, it is recommended not to blindly pursue high thermal conductivity LED aluminum substrate heat dissipation silicone grease.

Let's take a look at which coefficient of CPU thermal grease is better for LED lights of different powers.

1. For lamps below 10W, 1.0 or 1.3 is generally sufficient, and some low-end products on the market even use a coefficient of 0.8;

2. 10W-30W can be used with a thermal conductivity of 1.6-1.8;

3. For 30W to 50W, gray ones are generally preferred, with a thermal conductivity of 2.0 or higher;

4. For 50 to 100W, choose gray ones with thermal conductivity of 2.5 or 3.0.

In addition, if it is a surface mount lamp bead, due to its lower heat generation compared to the above lamp beads, you can choose a heat dissipation silicone grease with one level lower wattage than the corresponding one. Of course, if the product quality requirements are high, it is also good to choose the corresponding product according to the above suggestions.