2. Three factors that affect the pearlescent attenuation quality of LED lamps.
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 lamp. The size of this difference depends on the electrical parameters of LED, the design of lamps and the environment in which lamps are used.
First of all, choose what kind of LED lamp beads.
This is very important. The quality of LED beads can be said to be a very important factor. For example, 14mil LED lamp beads packaged with white light segment chips are made of ordinary epoxy resin, white light glue and packaging glue, and are lit at 30 degrees. After 1000 hours, the attenuation data is 70%. If it is encapsulated with D-class low attenuation glue, the light attenuation is 45% per thousand hours in the same aging environment; The light attenuation per thousand hours in the same aging environment is12% if encapsulated with C-type low attenuation glue; If it is encapsulated with B-type low attenuation glue, the light attenuation per thousand hours is-3% under the same aging environment; If the A-grade low-decay adhesive, under the same aging environment, the light decay per thousand hours is -6%.
Why do different packaging processes lead to such a big difference?
One of the main reasons is that LED chips are afraid of heat. It doesn't matter if it is heated to 100 degrees for a short time occasionally, for fear that being at high temperature for a long time will do great harm to LED chips.
Generally speaking, the thermal conductivity of ordinary epoxy resin is very small. Therefore, the LED chip will generate heat when it is on, but the thermal conductivity of ordinary epoxy resin is limited. Therefore, when you measure the temperature of the LED bracket from the outside of the LED light source at 45 degrees, the temperature of the chip center in the LED white light may exceed 80 degrees. The temperature node of LED is actually 80 degrees, so when the LED chip works at a temperature-saving temperature, it is very painful and accelerates the aging of LED light source.
When the LED chip works, the central temperature generates a high temperature of 100 degrees, and the heat can be immediately exported by 98% through the supporting feet, thus reducing the damage caused by heat. Therefore, when the temperature of LED lamp bead bracket is 60 degrees, the chip center temperature may only be 6 1 degree.
As can be seen from the above data, the light attenuation of LED lamps is directly determined by what kind of packaging technology is selected for LED lamp beads.
Secondly, the working environment temperature of LED light source.
According to the aging data of a single LED light source, if only one LED light source works and its ambient temperature is 30 degrees, the bracket temperature of a single LED light source will not exceed 45 degrees. At this time, the life of this LED will be ideal.
If there are 100 LED light sources working at the same time, and the interval between them is only 1 1.4mm, the bracket temperature of LED light sources around the lamp stack may not exceed 45 degrees, but those LED light sources in the middle of the lamp stack may reach a high temperature of 65 degrees. This is the test of LED light source. Then, the LED light sources gathered in the middle will theoretically have a faster light decay, while the LED light sources around the lamp stack will have a slower light decay.
However, if the LED beads are more than 25mm apart, the heat they radiate from each other will not be so accumulated. At this time, the temperature of each LED lamp bead bracket should be less than 50 degrees, which is more conducive to the normal work of LEDs.
If the LED works in a cold place, the annual average temperature may be only about 15 degrees, or even lower, so the life of the LED will be longer.
In other words, when the LED is working, there is a small fan blowing next to it to help it disperse the hot air, which is also very helpful for the life of the LED.
Anyway, everyone should know that LEDs are afraid of heat. The higher the temperature, the shorter the LED life, and the lower the temperature, the longer the LED life. The ideal working temperature of LED is, of course, between minus 5 and zero. But this is basically impossible.
So after we know the ideal working parameters of LED lamp beads, we should strengthen the functions of heat conduction and heat dissipation as much as possible when designing lamps. Anyway, the lower the temperature, the longer the life of LED.
Thirdly, the design of working electrical parameters of LED lamp beads.
According to the experimental results, the lower the driving current, the smaller the heat emitted by the LED white light, and of course the smaller the brightness. According to the investigation, in the design of LED solar lighting circuit, the driving current of LED is generally only 5-10 mA; For products with more beads, such as more than 500 beads or more, the driving current is generally only 10- 15mA, while the driving current of popular LED lighting is only 15- 18mA, and few people design the current above 20mA.
The experimental results also show that when the driving current is 1.4Ma, the cover is sealed, and the internal air temperature is 7 1 degree, the light attenuation of the low-attenuation product is zero in 1,000 hours and 3% in 2,000 hours, indicating that the use of this low-attenuation LED white light lamp in this environment has reached the maximum, which is a kind of damage to it.
Because the aging board used for aging has no heat dissipation function, the heat generated by LED operation can hardly be conducted to the outside. This is proved by experiments. The air temperature inside the aging board reached a high temperature of 10 1 degree, while the surface temperature of the cover on the aging board was only 53 degrees, a difference of several tens of degrees. This shows that the designed plastic cover basically has no heat conduction and heat dissipation function. However, in the general design of lamps, the functions of heat conduction and heat dissipation are considered. Therefore, to sum up, the design of working electrical parameters of LED lamp beads should be based on the actual situation. If the heat conduction and heat dissipation function of the lamp is good, it doesn't matter if the driving current of the LED white light lamp increases a little, because the heat generated by the LED lamp beads can be exported to the outside instantly, which is the best care for the LED. On the contrary, if the heat conduction and heat dissipation functions of lamps and lanterns