Why the LED chip is divided into different sizes such as 8mil, 9mil … 13 to 22mil, 40mil, etc.? How does different size chip affect the LED photoelectric characteristics?(mil is one measurement unit, a mil is one thousandth of an inch, that is 1mil=1/1000inch=0.00254cm=0.0254mm)
The LED chip can be divided into low-power, middle power and high-power chips according to different size. Based on customer requirements also can be divided into single-tube, digital, dot matrix. And the specific chip size depends on actual production levels of the different chip manufacturers, there are no specific rule. As long as the process is good enough, the small chip can increase the unit output and reduce costs, but the photoelectric performance won’t change fundamentally, so LED chip use higher current, their units’ current density are almost the same.
If 10mil chip using a current of 20mA, then the 40mil chip theoretically current can be increased 16 times to 320mA. However, consider the heat is the main problem in the high-current, so it’s luminous efficiency is lower than the small current, on the other hand, for big chip size, the resistance of the chip will be reduced, so the forward voltage will be decreased.