Three factors that affect LED lamp quality and luminescence decay
There should be some discrepancy between the data detected by a single LED white lamp on the aging board and the data detected when the LED white lamp is assembled into an aging lamp.
The magnitude of this difference depends on the electrical parameters of LED operation, lamp design, and the environment in which the lamp is used.
First, what kind of LED white light should you choose?
This is very important, and the quality of the LED white light is a very important factor. For example, the same LED white lamp encapsulated with a primer and white light glue, and a sealing glue made of ordinary epoxy resin, is also represented by a 14mil white light segment chip on a wafer, and a single one in a 30 degree environment. When the light is on, the decay data after 1,000 hours is 70%. When encapsulated with a Class D low-attenuation adhesive, the optical attenuation per 1,000 hours is 45% in the same aging environment. When encapsulated with a Class C low-attenuation adhesive, the 1,000-hour light decay is 12% in the same aging environment. When encapsulated with a Class B low-attenuation adhesive, the optical attenuation per 1,000 hours is -3% in the same aging environment. For Class A low rot adhesives, the light decay for 1000 hours is -6% in the same aging environment.
Why do different packaging processes make such a difference?
One of the main reasons is that LED chips are afraid of heat. Sometimes it can be heated to more than 100 degrees in a short period of time, but it is not a problem, we are afraid that it will be exposed to high temperature for a long time, which will cause great damage to the LED chip.
Generally, the thermal conductivity of ordinary epoxy resin is very small, so when the LED chip is lit, the LED chip must release heat, and the thermal conductivity of ordinary epoxy resin is limited, so the LED Measuring the temperature of the LED bracket from the outside of the white light may exceed 45 degrees, and the core temperature of the LED white light chip may exceed 80 degrees. Since the temperature node of LED is actually 80 degrees, the aging of LED white light will accelerate when the LED chip operates at the temperature preservation temperature.
When the LED chip is working, the core temperature will generate a high temperature of 100 degrees, and 98% of the heat can be immediately released through the bracket pin, which can reduce heat damage. Therefore, if the temperature of the LED white light bracket is 60 degrees, the temperature at the center of its chip may only be 61 degrees.
From the above data, we can see that the selection of LED white lamps with packaging process directly determines the light attenuation of LED lamps.
Second, the working environment temperature of LED lamp beads.
According to the aging data of single LED white light, when only one LED white light is lit and the ambient temperature is 30 degrees, the bracket temperature of single LED white light will not exceed 45 degrees. At the moment, the lifespan of this LED is ideal.
When 100 LED white lights are lit at the same time and the distance between them is only 11.4mm, the temperature of the bracket of LED white lights around the lamp pile may not exceed 45 degrees, but in the middle of the lamp pile Some LED white lights can reach high temperatures of 65 degrees. At this time, the LED lamp beads are tested. Next, the LED white light concentrated in the center will theoretically have faster light decay, and the LED white light around the lamp pile will have slower light decay.
However, if the LED lamp beads are more than 25mm apart, the heat they dissipate to each other will not accumulate as much, so at this time, the temperature of each LED white lamp bracket should be less than 50 degrees, and the normal operation of the LED Helpful.
If the LED operates in a cold location, where the average annual temperature may only be about 15 degrees or less, the LED will have a longer lifespan.
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 extend the life of the LED.
Anyway, you should know that LEDs are afraid of heat, and the higher the temperature, the shorter the LED lifespan, and the lower the temperature, the longer the LED lifespan. Of course, the ideal operating temperature for LEDs is between -5 degrees Celsius and 0 degrees Celsius. But this is basically impossible.
Therefore, after understanding the ideal operating parameters of LED lamp beads, we will do our best to enhance the functions of heat conduction and heat dissipation when designing the lamp. In any case, the lower the temperature, the longer the life of the LED.
Thirdly, the working electrical parameters of LED lamp beads are designed.
According to the experimental results, the lower the driving current of the LED white light, the less heat is emitted, and of course the less luminous intensity. According to research, in the design of LED solar lighting circuits, the driving current of LEDs is usually only 5-10mA. For products with a large number of lamp beads used in lamps and lanterns, such as more than 500 pieces, the drive current is generally only 10-15mA, while the drive current for typical LED application lighting is only 15-18mA. Yes, and few people design currents higher than 20mA.
The experimental results also show that under the driving current of 14mA, the internal temperature is 71 degrees under the environment of 14mA driving current, and when the internal temperature reaches 71 degrees, the light decay of the low attenuation product will last for 1,000 hours. zero, and the light attenuation for 2000 hours is 3%, indicating that the use of this low attenuation LED white lamp in such an environment has reached the maximum, and no matter how big it is, it is a kind of damage .
Since the aging board does not have a heat dissipation function, it is basically impossible to conduct the heat generated during LED operation to the outside. This has been experimentally proven. The temperature inside the aging board reaches a high temperature of 101 degrees, and the surface temperature of the lid of the aging board is only 53 degrees, a difference of several tens of degrees. This shows that the designed plastic cover basically has no function of thermal conductivity and heat dissipation. However, the general design of lamps and lanterns takes into account the functions of heat conduction and heat dissipation. Therefore, in summary, the design of the operating electrical parameters of LED lamp beads should be based on the actual situation, and if the heat conduction and heat dissipation functions of the lamp are very good, the operation of LED lamp beads will cause There is no problem even if the drive current of the LED white lamp is increased because the generated heat can be immediately released to the outside and the LED will not be damaged. On the other hand, if the lamp has decent heat conduction and heat dissipation capabilities, design the circuit a little smaller so that it dissipates less heat.