On the LED Lamp heat knowledge
1, pn knot temperature
LED optical parameters and pn junction temperature has a great relationship. The general work in the small current IF <10mA, or 10 ~ 20 mA long continuous light LED temperature is not obvious. If the ambient temperature is high, the main wavelength or λp of the LED will drift to the long wavelength, BO will fall, especially the lattice, large display temperature rise on the stability of the LED should be designed specifically designed for scattered ventilation.
The main wavelength of the LED with the temperature relationship can be expressed as λp (T ') = λ0 (T0) + △ Tg × 0.1nm / ℃
As can be seen from the equation, when the junction temperature increases by 10 ° C, the wavelength drifts to the long wave by 1 nm, and the uniformity and uniformity of the emission are deteriorated. This is for the lighting of the light source requirements for miniaturization, LED Lamp intensive arrangement to improve the intensity per unit area, the brightness of the design should pay attention to the use of a good cooling of the lamp or special equipment to ensure long-term work.
2, thermal resistance Rth
The ratio of the temperature difference between the heat flow channel and the dissipated power on the channel; when the heat conduction steady state is reached after the LED is lit, LED Lamp the chip's surface is dissipated with 1W of power, and the temperature of the chip pn junction is the same as that of the connected or aluminum The temperature difference between temperatures is called the thermal resistance Rth, in ° C / W. The lower the value, the faster the heat in the sheet is transferred to the holder or the aluminum substrate.
3, failure rate λ
Failure rate λ refers to a group of LED devices in the light after a long time, how many appear "dead light" phenomenon. This is a measure of the quality of these LED components of the key indicators. If the work within 10 hours without "dead light" phenomenon, indicating that the failure rate is better, that failure rate of 0.
4, LED storage ambient temperature and operating temperature
Conventional, LED storage environment temperature should be -40 ℃ ~ +100 ℃. In the packaging of LED, sometimes in order to make plastic or phosphor fast drying, at a temperature of 150 ℃ for 1 to 2 hours, which has an impact on the LED, to be verified. The LED operating temperature is -30 ℃ ~ +80 ℃, LED Lamp but the relationship between the working temperature and thermal resistance. LED in the work, it is best to keep its pn junction temperature below 100 ℃.
5, life expectancy
LED devices under normal operating conditions, the longer the half-light fade, indicating that the longer the life of LED. According to the theoretical calculation of up to 100,000 hours or more. But at present due to materials, manufacturing technology and other reasons, the market life of LED devices can only reach 2 to 3 million hours. LED device life and the use of the system when the cooling conditions, the light efficiency is directly related.
6, anti-static indicators
Do the LED Lamp device to pay attention to anti-static. Whether in the transport state, or in the assembly process, there may be static damage, to pay special attention to anti-static. General LED do a good job, the bipolar open anti-static indicators should be within 500V.
7, other indicators
LED is sealed by epoxy resin and other plastic. LED Lamp Due to the role of time and chemical, will make the plastic permeability of the package worse. Sometimes make the colloid yellowing turbidity, affecting light; some will make plastic glass and broken. These will make the LED device performance changes, so fail to reach the original technical indicators, thus affecting its light efficiency and service life.