LED lamps light decay processing skills
There must be some discrepancies between the data detected by a single white LED lamp on the aging board and the data detected when the white LED lamp is assembled into a lamp aging.
The size of this difference depends on the electrical parameters of the LED working, the design of the lamp, and the environment in which the lamp is used.
First of all, what kind of white LED light to choose.
This is very important. The quality of the LED white light can be said to be a very important factor. To cite some examples, the same is represented by Epistar 14mil white light segment chips, and the LED white light encapsulated with ordinary epoxy resin primer, white light glue and packaging glue, a single light is lit in an environment of 30 degrees, one After a thousand hours, the attenuation data is 70% light attenuation; if it is packaged with D-type low-attenuation glue, under the same aging environment, the thousand-hour light attenuation is 45%; if C-type low-attenuation glue is packaged, under the same aging environment , 1000-hour light decay is 12%; if type B low decay glue is encapsulated, under the same aging environment, 1000 hours light decay is -3%; if type A low decay glue, under the same aging environment, 1000 hours light decay Decay is -6%.
Why do different packaging processes cause such big differences?
One of the main reasons is that the LED chip is afraid of heat. Occasionally, it does not matter if it is heated to more than 100 degrees in a short period of time. I am afraid that the long-term high temperature will cause great damage to the LED chip.
Generally speaking, the thermal conductivity of ordinary epoxy resin is very small. Therefore, when the LED chip lights up, the LED chip emits heat, while the ordinary epoxy resin has limited thermal conductivity. Therefore, when you switch from the LED white light When the temperature of the LED bracket is measured externally to be 45 degrees, the core temperature of the chip in the white LED lamp may exceed 80 degrees. The temperature node of the LED is actually 80 degrees. Then, when the LED chip works at the temperature-saving temperature, it is very tormented, which accelerates the aging of the white LED light.
When the LED chip is working, the core temperature produces a high temperature of 100 degrees, and it can immediately take out 98% of the heat through the bracket pins, thereby reducing the heat damage to it. Therefore, when the temperature of the LED white lamp holder is 60 degrees, the core temperature of its chip may be only 61 degrees.
It can be seen from the above data that the choice of packaging technology for white LED lamps directly determines the light decay of LED lamps.
The second is the design of working electrical parameters of LED lamp beads.
According to the experimental results, the lower the driving current of the LED white lamp, the smaller the heat emitted, of course, the lower the brightness. According to the survey, the design of LED solar lighting circuit, the driving current of LED is generally only 5-10mA; the number of lamp beads used in lamps and lanterns has a large number of products, such as 500 or more, the driving current is generally only 10-15mA However, the driving current of the general popular LED application lighting is only 15-18mA, and very few people design the current to be above 20mA.
The experimental results also show that under the driving current of 14mA, and the cover is airtight, and the air temperature inside reaches 71 degrees, the low decay product has zero luminous decay in 1000 hours and 3% in 2000 hours. This shows that the use of this low-decay LED white light in such an environment has reached its maximum, and no matter how big it is, it will be a kind of damage.
Because the aging board used for aging has no heat dissipation function, the heat generated when the LED is working is basically unable to be conducted to the outside. This is proved experimentally. The air temperature inside the aging board has reached a high temperature of 101 degrees, and the surface temperature of the cover on the aging board is only 53 degrees, a difference of tens of degrees. This shows that the designed plastic cover basically does not have the function of heat conduction and heat dissipation. However, in general lamp design, the function of heat conduction and heat dissipation is considered. Therefore, in summary, the design of the working electrical parameters of the LED lamp beads should be based on the actual situation. If the heat conduction and heat dissipation function of the lamp is good, it does not matter if the driving current of the LED white lamp increases a little, because the LED lamp beads work. The heat can be exported to the outside in an instant, and there is no damage to the LED, which is the best care for the LED. On the contrary, if the heat conduction and heat dissipation function of the lamp is so-so, it is best to design the circuit smaller to let it emit less heat.
The third is the working environment temperature of the LED lamp beads.
According to the aging data of a single white LED light, if only one white LED light is on and working, and at the same time, the ambient temperature is 30 degrees, then the temperature of the bracket when a single white LED light is working will not be More than 45 degrees. At this time, the life of this LED will be ideal.
If there are 100 white LED lights working at the same time, and the interval between them is only 11.4mm, then the temperature of the bracket of the white LED lights around the lamp stack may not exceed 45 degrees, but the middle of the lamp stack Those LED white lights may reach a high temperature of 65 degrees. At this time, the LED lamp bead is a test. Then, the white LED lights gathered in the middle will have a faster light decay in theory, while the white LED lights around the pile will have a slower light decay. Distance is important
But if the LED lamp beads are more than 25mm apart, the heat radiated from each other will not accumulate so much. At this time, the temperature of each LED white lamp bracket should be less than 50 degrees, which is more conducive to the normal operation of the LED.
If the working environment of the LED is in a relatively cold place, the average temperature throughout the year may be only about 15 degrees, or less, then for the LED, the lifespan will be longer. Enlarge the pad and heat sink to increase heat dissipation.
Or, when the LED is working, there is a small fan blowing next to it to dissipate the heat, which is also very helpful to the life of the LED. But it is not easy to operate.
Anyway, everyone should know that LEDs are resistant to heat. The higher the temperature, the shorter the life of the LED, and the lower the temperature, the longer the life of the LED. The ideal working temperature of the LED is of course between minus 5 and zero degrees. But this is basically impossible.
Therefore, after we understand the ideal working parameters of the LED lamp beads, we will try our best to strengthen the heat conduction and heat dissipation functions when designing the lamps. Anyway, the lower the temperature, the longer the life of the LED.
The ambient temperature of the lamp is also important and should be taken into consideration.
