Talk about the LED heat and heat dissipation
Talk about the LED heat and heat dissipation
In recent years, LED technology has been touted as the next generation of lighting technology, and with the increase in LED power supplies, cooling has become a growing concern. Researchers have long observed that the light decline or life of LEDs is directly related to their jointing temperature, so if the heat is not smooth, high temperature and short life.
Unlike incandescent and fluorescent lamps in the past, the energy loss is large, but most of the energy is emitted directly through infrared, and the heat of the light source is very low.LEDs convert all energy (except that consumed by visible light) into heat. Electronic products are gradually becoming the exception of high-density, high-density, Led products, to solve the problem of Led heat dissipation has become the main problem of today's Led performance improvement and the development of the Led industry.
LED heat cause:
LED heat cause is added power are not converted into light energy, part of the conversion into heat energy. Indicator light is only 100lm/W, electro-optical conversion efficiency of about 20% to 30%. That is, about 70% of the electricity is converted to heat.
In particular, the LED joint temperature occurs by two factors:
1. Both internal inefficiencies. That is to say, when the electrons are combined with the holes, photons cannot be generated 100%, usually due to “current leakage” which reduces the carrier complex rate in the PN region. The leakage current multiplied by the voltage is the power of this part. In other words, it is converted to heat, but this part does not occupy the main components, because the efficiency of internal photons is already close to 90%.
2. None of the internally generated photons can be shot outside the chip, and part of the main reason why they end up converted to heat is that this is called external quantum efficiency is only about 30%, and most of it is converted to heat.
As mentioned above, incandescent lamps have a low light efficiency but only about 15lm/W, but almost all the electricity is converted to light energy and emitted. Most of the radiation is infrared, so the light efficiency is low, but eliminates the heat dissipation problem.
LED heat dissipation solutions:
The heat dissipation of Led mainly starts from two aspects, Led chip heat dissipation before and after packaging and Led lamp heat dissipation.Led chip heat dissipation is mainly related to the process of substrate and circuit selection, because any LED can make lamps, so the heat generated by the LED chip is eventually dispersed into the air through the lamp housing. If you can't dissipate heat well, the heat capacity of the LED chip will be small, so if some heat accumulates, the chip's connection temperature will increase rapidly, and if it works at high temperatures for a long time, its life will be shortened rapidly. But this heat has to go through multiple pathways to direct the chip to actually reach the outside air. In particular, the LED chip generates heat from the metal heat block, which generates heat from the solder to the PCB on the aluminum substrate, which reaches the aluminum heat sink through the thermally conductive adhesive. Therefore, LED lighting involves both heat diffusion. the way LED enclosures are cooled depends on the size of the power supply and the location where it is used. There are mainly the following cooling methods:
Aluminum heat pins: the most common thermal method, using aluminum heat pins as part of the enclosure to increase the cooling area.
Thermally Conductive Plastic Enclosures: Plastic enclosures are injection molded filled with thermally conductive materials to increase the thermal conductivity and heat dissipation of the plastic enclosure.
Aerofluidics: Utilizing a barnacle shape to create convection air is the cheapest way to dissipate heat.
Fan: Inside the lamp shell is a high efficiency fan with long service life to enhance cooling, low cost and good effect. But changing the fan is troublesome and not suitable for outdoor use. This design is relatively rare.
Heat exchanger: Using heat exchanger technology, the heat in the LED wafer is induced to the hot pins of the housing. Large scale lighting such as street lights is a typical design.
Surface radiant heat dissipation treatment: The surface of the lamp housing is radiant heat dissipation treatment, applying sishengweihua radiant heat dissipation coating, which can emit heat from the surface of the lamp housing.
ZS-411 radiant heat cooling coating has high thermal conductivity
and large thermal surface area, and has high emissivity over a considerable wavelength range (1-20m), which can significantly improve the overall performance including conduction, convection and radiant heat.
The coatings utilize high-performance thermal solutions with specific properties of visible and near-infrared reflectance, thermal infrared emissivity, and high stability with good physical properties, chemical properties, and good constructability compounding due to the coalescence of inorganic colloidal particles of less than 100 nm that create binding forces. By adding carbon nanotubes and other materials with high thermal conductivity and radioactivity to the coating solution, it is possible to constitute nanomaterials with macroscopic, microscopic, and rough morphology on the surface of the coating, thus greatly increasing the contact area between the heat sink and the outside, and greatly improving the heat dissipation effect. By adding a variety of spinel, which is transferred by electrons, as a composite infrared emitter, the impurity energy level is increased and the infrared radiation coefficient is improved, thus maintaining thermal stability,heat resistance.
The overall luminous efficiency of LED is low, so the joint temperature is high and the life is shortened. In order to extend the life and reduce the joint temperature, attention must be paid to heat dissipation.
Unlike incandescent and fluorescent lamps in the past, the energy loss is large, but most of the energy is emitted directly through infrared, and the heat of the light source is very low.LEDs convert all energy (except that consumed by visible light) into heat. Electronic products are gradually becoming the exception of high-density, high-density, Led products, to solve the problem of Led heat dissipation has become the main problem of today's Led performance improvement and the development of the Led industry.
LED heat cause:
LED heat cause is added power are not converted into light energy, part of the conversion into heat energy. Indicator light is only 100lm/W, electro-optical conversion efficiency of about 20% to 30%. That is, about 70% of the electricity is converted to heat.
In particular, the LED joint temperature occurs by two factors:
1. Both internal inefficiencies. That is to say, when the electrons are combined with the holes, photons cannot be generated 100%, usually due to “current leakage” which reduces the carrier complex rate in the PN region. The leakage current multiplied by the voltage is the power of this part. In other words, it is converted to heat, but this part does not occupy the main components, because the efficiency of internal photons is already close to 90%.
2. None of the internally generated photons can be shot outside the chip, and part of the main reason why they end up converted to heat is that this is called external quantum efficiency is only about 30%, and most of it is converted to heat.
As mentioned above, incandescent lamps have a low light efficiency but only about 15lm/W, but almost all the electricity is converted to light energy and emitted. Most of the radiation is infrared, so the light efficiency is low, but eliminates the heat dissipation problem.
LED heat dissipation solutions:
The heat dissipation of Led mainly starts from two aspects, Led chip heat dissipation before and after packaging and Led lamp heat dissipation.Led chip heat dissipation is mainly related to the process of substrate and circuit selection, because any LED can make lamps, so the heat generated by the LED chip is eventually dispersed into the air through the lamp housing. If you can't dissipate heat well, the heat capacity of the LED chip will be small, so if some heat accumulates, the chip's connection temperature will increase rapidly, and if it works at high temperatures for a long time, its life will be shortened rapidly. But this heat has to go through multiple pathways to direct the chip to actually reach the outside air. In particular, the LED chip generates heat from the metal heat block, which generates heat from the solder to the PCB on the aluminum substrate, which reaches the aluminum heat sink through the thermally conductive adhesive. Therefore, LED lighting involves both heat diffusion. the way LED enclosures are cooled depends on the size of the power supply and the location where it is used. There are mainly the following cooling methods:
Aluminum heat pins: the most common thermal method, using aluminum heat pins as part of the enclosure to increase the cooling area.
Thermally Conductive Plastic Enclosures: Plastic enclosures are injection molded filled with thermally conductive materials to increase the thermal conductivity and heat dissipation of the plastic enclosure.
Aerofluidics: Utilizing a barnacle shape to create convection air is the cheapest way to dissipate heat.
Fan: Inside the lamp shell is a high efficiency fan with long service life to enhance cooling, low cost and good effect. But changing the fan is troublesome and not suitable for outdoor use. This design is relatively rare.
Heat exchanger: Using heat exchanger technology, the heat in the LED wafer is induced to the hot pins of the housing. Large scale lighting such as street lights is a typical design.
Surface radiant heat dissipation treatment: The surface of the lamp housing is radiant heat dissipation treatment, applying sishengweihua radiant heat dissipation coating, which can emit heat from the surface of the lamp housing.
ZS-411 radiant heat cooling coating has high thermal conductivity
and large thermal surface area, and has high emissivity over a considerable wavelength range (1-20m), which can significantly improve the overall performance including conduction, convection and radiant heat.
The coatings utilize high-performance thermal solutions with specific properties of visible and near-infrared reflectance, thermal infrared emissivity, and high stability with good physical properties, chemical properties, and good constructability compounding due to the coalescence of inorganic colloidal particles of less than 100 nm that create binding forces. By adding carbon nanotubes and other materials with high thermal conductivity and radioactivity to the coating solution, it is possible to constitute nanomaterials with macroscopic, microscopic, and rough morphology on the surface of the coating, thus greatly increasing the contact area between the heat sink and the outside, and greatly improving the heat dissipation effect. By adding a variety of spinel, which is transferred by electrons, as a composite infrared emitter, the impurity energy level is increased and the infrared radiation coefficient is improved, thus maintaining thermal stability,heat resistance.
The overall luminous efficiency of LED is low, so the joint temperature is high and the life is shortened. In order to extend the life and reduce the joint temperature, attention must be paid to heat dissipation.