Industry News

"Three days" high temperature is difficult to block, how to break the LED heat?

2018-11-06
Continuously at high temperatures, the body is prone to a series of adverse reactions:

1. The impact on the circulatory system. During high-temperature operation, the skin's blood vessels dilate, and a large amount of sweat causes the blood to concentrate, resulting in increased cardiac activity, rapid heartbeat, elevated blood pressure, and increased cardiovascular burden.

2. The impact on the digestive system. High temperature has an inhibitory effect on salivation. Reduce the secretion of gastric juice, slow down the gastric peristalsis, resulting in loss of appetite; a large amount of sweating and loss of chloride, so that the acidity of gastric juice is reduced, easily lead to indigestion. In addition, high temperatures can slow the movement of the small intestine and form other gastrointestinal diseases.

3. The impact on the urinary system. At high temperatures, most of the body fluids of the human body are discharged by the sweat glands, and the amount of water and salt discharged through the kidneys is greatly reduced, so that the urine is concentrated and the burden on the kidneys is aggravated.

4. The impact on the nervous system. Under the action of high temperature and heat radiation, the working ability of the muscle, the accuracy and coordination of the movement, the speed of the brain reaction and the attention decreased.

High temperature will have such a big impact on the human body, so what about LED light sources?

It is well known that the electrical energy added by the LED under working conditions is not completely converted into light energy, but a part is converted into heat energy. As the fourth generation of light source, LED has great development prospects due to its advantages of energy saving, environmental protection and long life. However, the LED is extremely sensitive to temperature, and the junction temperature rise will affect the LED life, light efficiency, light color (wavelength), color temperature, light shape (light distribution), and forward voltage, maximum injection current, luminosity, color, and electrical parameters. And reliability, etc.

First, too high a temperature can cause permanent damage to the LED. When the LED temperature exceeds the carrying temperature of the chip, the luminous efficiency of the LED will be rapidly reduced, resulting in significant light decay and damage. In addition, if the junction temperature of the LED is too high, the packaging material will change to a rubbery state and the thermal expansion coefficient will rise sharply, resulting in LED open circuit and failure damage.

Second, an increase in temperature will shorten the life of the LED. The life of an LED is manifested by its light decay, which means that the time is long and the brightness is getting lower and lower until it is finally extinguished. In addition, under temperature conditions, micro-defects in the material also accelerate the light decay of the LED device. At the same time, the higher the operating temperature, the faster the process will proceed, which is another major cause of LED light decay. In addition, the light decay of the phosphor is also a major cause of the LED light decay, because the phosphor's attenuation at high temperatures is very serious.

The problem of heat dissipation is a major obstacle in the development of LEDs for use as lighting objects. Therefore, reducing the temperature of LEDs by various means has become a problem discussed by major manufacturers. Since the heat dissipation of LEDs is now more and more important to people, various heat dissipation technologies have also been applied to LED lighting technology!

Since the LED light source itself has no radiation heat dissipation function, the heat dissipation path of the LED lighting fixture can only derive heat through a heat sink closely combined with the LED lamp bead. Any radiator, in addition to being able to quickly transfer heat from the heat source to the surface of the radiator, the most important thing is to rely on convection and radiation to dissipate heat into the air. Thermal conduction only solves the heat transfer path, and thermal convection is the main function of the heat sink. The heat dissipation performance is mainly determined by the heat dissipation area, shape, and natural convection strength. Thermal radiation is only an auxiliary function.