Actually this question can, in turn, is also designed to be a good LED lamps and lanterns, it allowed by the internal environment should be a certain temperature. This is because the junction temperature of the LED chip is to determine the LED chip droop (life), the main reasons for the LED junction temperature, of course, also by the environmental temperature, so as long as know that allow the LED junction temperature, also can calculate the internal environmental temperature of LED lamps and lanterns. But in which there are at least three thermal resistance, is the thermal resistance of LED chip junction to case theta jc, shell and LED to the thermal resistance of the aluminum plate surface, after soldering, copper foil, and insulation to it to the aluminum plate, but is one of the main insulation layer of thermal resistance, collectively known as theta lv, the third is the thermal resistance aluminum plate to the air inside the blister theta la.
Take 3014 type LED, for instance, it is the thermal resistance of theta jc 90 ℃ / W, because it is only 0.1 W, so the temperature difference between inside and outside also is 9 ℃. Aluminum plate thermal resistance is 1 ℃ / W, for a 10 W since all 10 W LED lamps and lanterns is installed in the same block of aluminum substrate, so its total temperature is 10 ℃, a total of 19 ℃ temperature difference, the final theta la is hard to estimate, because it is related to whether the air circulation, in the case of internal air flow, the temperature difference is only about 1 ℃ or so, so add up to a total of 20 ℃,. That is to say, the LED junction temperature is equal to the ambient temperature and 20 ℃.