The fire rating of thermal conductive silicone film that we often refer to actually refers to the flame retardant rating of thermal conductive silicone film. The flame retardant rating of thermal conductive silicone film is a relatively important parameter among the many performance parameters of thermal conductive silicone film. According to the test report of the thermal conductive silicone film, it can be concluded that all the thermal conductive silicone films we produce have a flame retardant rating of UL-94 V0. Previously, we introduced "What is thermal conductivity? Thermal conductivity of thermal conductive materials and testing methods". Today, we will introduce the criteria for determining the flame retardant grade of thermal conductive silicone sheets and the differences in testing.

The standards and differences involved in the flame retardant grade HB of thermal conductive silicone sheets:

Standard: UL94 Rating: HB

Specific requirements for determining the level:

1. The combustion distance is 75mm, the sample thickness is 3.0-13mm, and the combustion speed is ≤ 40mm/min,

2. Burning distance 75mm, sample thickness<3.0mm, burning speed ≤ 75mm/min,

3. The flame stops before the 100mm mark;

4. When the combustion distance is 75mm, the sample thickness is 3.0mm+0.2mm, and the combustion speed is ≤ 40mm/min, the minimum thickness of 1.5mm should be automatically accepted as this level.

Standard: GB/T 2408 IEC60695-11-10 Determination level: HB, HB40, HB75

Thermal conductive silicone sheet flame retardant HB grade evaluation:

After removing the ignition source, there should be no obvious flame burning;

If the test sample continues to have flame combustion after removing the ignition source, the flame front should not pass through the 100mm marking line;

3. The combustion distance is 75mm, the sample thickness is 3.0-13mm, and the combustion speed is ≤ 40mm/min; Burning distance 75mm, sample thickness ＜ 3.0mm, burning speed ≤ 75mm/min

4. The combustion distance is 75mm, the sample thickness is 3.0mm ± 0.2mm, and the combustion speed is ≤ 40mm/min; When the minimum thickness is reduced to 1.5mm, it should be automatically accepted as this level.

Materials classified as HB40 should meet one of the following criteria:

1. There should be no obvious flame burning after removing the ignition source;

2. If the test sample continues to have flame combustion after removing the ignition source, the flame front should not pass through the 100mm marking line;

3. If the flame front passes through the 100mm marking line, the linear combustion rate should not exceed 40mm/min.

HB75 class: Even if the flame front passes through the 100mm marking line, the linear combustion rate of the material should not exceed 75mm/min