In recent years, with the rapid advancement of LED chip technology, the commercial application of LEDs has become very mature. LED products are known as “green light sources” because of their small size, low power consumption, long service life, high brightness, environmental protection, sturdiness and durability, as well as significant energy-saving LED lamps. Using ultra-bright and high-power LED light source, with high-efficiency power supply, it can save more than 80% of electricity than traditional incandescent lamps, and the brightness is 10 times that of incandescent lamps under the same power. The long life span is more than 50,000 hours, which is more than 50 times that of traditional tungsten filament lamps. LED adopts highly reliable advanced packaging technology-eutectic welding, which fully guarantees the long life of LED. The luminous visual efficiency rate can be as high as 80lm/W or more, a variety of LED lamp color temperatures are available, high color rendering index, and good color rendering. LED light string LED technology is advancing with each passing day, its luminous efficiency is making amazing breakthroughs, and the price is constantly decreasing. As a lighting product, it has penetrated into thousands of households and streets.
However, LED light source products are not without any shortcomings. Like all electrical products, LED lights will generate heat during use, leading to an increase in ambient temperature and their own temperature. LED is a solid-state light source with a small light-emitting chip area and a large current density through the chip during operation; while the power of a single LED chip is relatively small, and the output luminous flux is also low. Therefore, when practically applied to lighting equipment, most lamps require The combination of multiple LED light sources makes the LED chip denser. And because the photoelectric conversion rate of the LED light source is not high, only about 15% to 35% of the electrical energy is converted into light output, and the rest is converted into heat energy. Therefore, when a large number of LED light sources work together, a large amount of heat energy will be generated. If this heat cannot be dissipated as quickly as possible, it will cause the junction temperature of the LED light source to rise, reduce the photons emitted by the chip, reduce the color temperature quality, accelerate the aging of the chip, and shorten the life of the device. Therefore, thermal analysis and optimal design of the heat dissipation structure of LED lamps become extremely critical.
Based on years of development experience of LED products in the industry, a very complete design theory system has been formed. As a lighting product structure designer, it is equivalent to standing on the shoulders of giants. However, it is not that it is so easy to reach the top on the shoulders of giants. There are many problems that need to be overcome in daily design. For example, from the perspective of cost, in the design, it is necessary to meet the heat dissipation requirements of the product, but also to minimize the cost; currently, the most commonly used method on the market is to use aluminum alloy fins for heat dissipation. In this way, how do designers To determine the gap distance between the fin and the fin and the height of the fin, as well as the influence of the structure of the product on the airflow and the orientation of the light-emitting surface, will lead to inconsistent heat dissipation. These are problems that plague designers.
In the design process of LED lamps, there are many ways to reduce the LED junction temperature and ensure the life of the LED: ① Strengthen heat conduction (there are three ways of heat transfer: heat conduction, convection heat exchange and radiation heat exchange), ②, select Low thermal resistance LED chips, ③, under-load or overload use the rated power or current of the LED (it is recommended to use 70%~80% of the rated power), which can effectively reduce the LED junction temperature.
Then to strengthen heat conduction, we can adopt the following methods: ①, a good secondary heat dissipation mechanism; ②, reduce the thermal resistance between the installation interface of the LED and the secondary heat dissipation mechanism; ③, enhance the contact between the LED and the secondary heat dissipation mechanism The thermal conductivity of the surface; ④, the structural design using the principle of air convection.
Therefore, heat dissipation is an insurmountable gap for product designers in the lighting industry at this stage. At this point, I believe that with the revolutionary advancement of technology, the impact of heat dissipation on LEDs will gradually become smaller. We are also trying to find ways to reduce the junction temperature of LEDs, ensure LED life, and make cost-effective products through application methods. .
Post time: Oct-22-2020