1. SMD LED light beads high quality you generally you look for some of these well-known brands will be more reliable, expand the quality of photoelectric or more reliable, the industry has a lot of good quality, such as osram, Corey. Nichia. Toyota Synthesis. Specifically you can search to see. Expand LED company is located in Shenzhen.
2.Three factors affecting the quality of LED light beads light failure
The data detected by a single led white light on the aging board must be a little different from the data detected when the led white light is assembled into a fixture for aging. The size of this difference depends on the electrical parameters of the LED work and the design of the fixture, as well as the environment in which the fixture is used.
First, what kind of LED beads to choose.
This is very important, the quality of LED light beads can be said to be very important factors. To give some examples, the same wafer 14mil white segment chip as a representative, with ordinary epoxy resin to do the bottom glue and white glue and encapsulation glue encapsulation out of the LED lamp beads, a single light in the environment at 30 degrees, one thousand hours, the attenuation data for the light failure of 70%; if the D class of low-failure glue encapsulation, in the same aging environment, the thousand hours of light failure of 45%; if the C class of low-failure glue encapsulation, in the Under the same aging environment, the light attenuation is 12% per thousand hours; if the B class low attenuation glue package, under the same aging environment, the light attenuation is -3% per thousand hours; if the A class low attenuation glue, under the same aging environment, the light attenuation is -6% per thousand hours.
Why do different encapsulation processes lead to such big differences?
One of the main reasons is that LED chips are afraid of heat. Occasionally a short period of time more than a hundred degrees of heat, it does not matter, afraid of the fear of being under a high temperature for a long time, is a great damage to the LED chip.
Generally speaking, the thermal conductivity of ordinary epoxy resin is very small, therefore, when the LED chip is lit to work, the LED chip to emit heat, and ordinary epoxy resin has limited thermal conductivity, so when you measure the temperature of the LED bracket from the outside of the LED light source is 45 degrees, the chip center temperature inside the LED white light is likely to be more than 80 degrees.The temperature node of LED is actually 80 degrees, then, when the LED chip is working in the temperature of the temperature of the node, it is very suffering, which accelerates the aging of the LED light source.
When the LED chip is working, the center temperature produces a high temperature of 100 degrees, it can immediately through the bracket pins 98% to lead the heat out, thus reducing the heat damage to it. So, when the LED lamp bead bracket temperature is 60 degrees, its chip center temperature may be just 61 degrees.
From the above data, we can see that the choice of what kind of encapsulation process of the LED lamp beads, directly determines the LED lamps and lanterns of the light failure situation.
Secondly, LED light source working environment temperature.
According to the data of single LED light source when aging, LED light source if only one lit work, at the same time, it is located in the ambient temperature is 30 degrees, then, the single LED light source work when the bracket temperature will not exceed 45 degrees. At this time, the life of this LED will be ideal.
If there are 100 LED light source at the same time light work, the interval between them is only 11.4mm case, then, the light pile of the periphery of the LED light source of the bracket temperature may not be more than 45 degrees, but the middle of the pile of those LED light source is possible to reach a high temperature of 65 degrees. At this time, the LED light source is a test. Then, those LED light sources gathered in the middle, theoretically, the light decay will be a little faster, while the LED light sources around the light stack, the light decay will be a little slower.
However, if the LED lamp beads are more than 25mm apart, then, the heat they emit to each other will not be so accumulated, at this time, the temperature of each LED lamp bead bracket should be less than 50 degrees below, it is more conducive to the normal operation of the LED.
If the LED are working in a colder environment, where the average temperature throughout the year may only be about 15 degrees or less, that's a much longer life for the LED.
Or, when the LED is working, there is a small fan blowing next to it to help it dissipate the heat, which is also quite helpful for the life of the LED.
Anyway, you should know that LED is afraid of heat, the higher the temperature, the shorter the LED life, the lower the temperature, the longer the LED life. the ideal working temperature of the LED is of course between negative 5 and zero degrees. But this is basically impossible.
So, once we understand the ideal working parameters of LED light beads, we try to enhance the thermal conductivity and heat dissipation as much as possible when designing the lamps and lanterns. Anyway, the lower the temperature, the longer the LED life.
Again, the working electrical parameters of the LED beads are designed.
According to the experimental results, LED white light in the case of the lower drive current, the smaller the emission of heat, of course, the brightness is also smaller. According to the survey, LED solar lighting circuit design, LED drive current is generally only 5-10mA; lamps and lanterns used in the number of lamp beads with a large number of products, such as more than 500 or more, drive current is generally only 10-15mA, and the general public of the LED application of the drive current of the lamp, only 15-18mA, very few people to design the current to 20mA or more!
And experimental results also show that, in the 14mA drive current, and, plus a cover impermeable, inside the air temperature reaches 71 degrees under the environment, low-life products, thousands of hours of light decay is zero, 2000 hours of light decay of 3%, which shows that this low-failure LED white light used in such an environment has reached its maximum, and then big is a damage to it.