LED semiconductor

LED is known as the fourth generation lighting source or green light source. It has the characteristics of energy saving, environmental protection, long life and small size. It can be widely used in various fields such as indication, display, decoration, backlight, general lighting and urban night scene. Various enterprises have launched a fierce technical competition in LED research and development. However, LED heat dissipation has always been an urgent problem to be solved.

The reason why the LED generates heat is that part of the input electrical energy is not completely converted into light energy, but into heat energy. At present, the luminous efficiency of LED is only 100lm/W, and its electro-optical conversion efficiency is about 20-30%, that is, about 70% of the electric energy is converted into heat energy.

LED junction temperature is caused by two main factors:

1. The internal quantum efficiency is not high, that is, when electrons and holes recombine, not all photons are generated. This is called "current leakage", which leads to a decrease in the recombination rate of carriers in the PN region. The leakage current multiplied by the voltage is this part of the power, which is converted into heat energy. But this is not the main component, because the internal photon efficiency is currently close to 90%.

2. The photons generated inside cannot all escape the chip and are converted into heat. This is the main factor, because at present this conversion rate, known as the external quantum efficiency, is only about 30%, and most of it is converted into heat.

Although the luminous efficiency of the incandescent lamp is very low, only about 15lm/W, it converts almost all the electrical energy into light energy and radiates it out. Because most of the radiation energy is infrared, the light efficiency is low, but it avoids the heat dissipation problem.

Nowadays, people pay more and more attention to the heat dissipation of LEDs, because the light attenuation and life of LEDs are directly related to the junction temperature, and poor heat dissipation will cause the junction temperature to rise, thereby shortening the life.

The LED chip will generate high heat in a very small volume, and the heat capacity of the LED itself is very small, so the heat must be conducted out at the fastest speed, otherwise the junction temperature will rise. In order to guide the heat from the chip to the maximum extent, materials with good thermal conductivity have been developed for LED lamps and other products, such as thermal conductive silicone grease and other thermal interface.

For the LED market has developed targeted products, in addition to good thermal conductivity also gives the material other properties to facilitate customer use.

Helis thermal grease series, with delicate paste, low thermal resistance, high thermal conductivity characteristics.