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The data detected by a single LED white lamp on the aging board is certainly a little different from the data detected by assembling the LED white lamp into a lamp when it is aging.
The size of the difference depends on the electrical parameters of the LED when it works, the design of the lamp, and the environment in which the lamp is used.
First, choose what kind of LED white light.
This is very important, the quality of LED white light can be said to be a very important factor. For example, in the same case, taking the 14mil white segment chip as a representative, the LED white lamp packaged with the base glue, white glue and sealing glue made of ordinary epoxy resin is lit in the environment of 30 degrees, and the attenuation data is 70% after 1000 hours; if it is packaged with class D low-aging glue water, in the same aging environment, the attenuation of 1000 hours is 45%; In the same aging environment, the aging time of 1000 hours is 12% for class C low aging glue package; 3% for class B low aging glue package; 6% for class a low aging glue package.
Why do different packaging processes lead to big differences?
The main reason is that led chips are not hot. It doesn't matter if the temperature is more than 100 degrees in a short time. It's a great damage to the LED chip if it's afraid of being under high temperature for a long time.
Generally speaking, the thermal conductivity of ordinary epoxy resin is very small. Therefore, when the LED chip lights up, the LED chip will emit heat, while 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 white light to 45 degrees, the chip center temperature in the LED white light may exceed 80 degrees. The temperature node of LED is actually 80 degrees, so when the LED chip works in the temperature saving temperature, it is very suffering, which speeds up the aging of LED white light.
When the LED chip is working, the center temperature produces a high temperature of 100 degrees. It can immediately guide out 98% of the heat through the pin of the bracket, so as to reduce the heat damage to it. Therefore, when the temperature of the LED white light bracket is 60 degrees, the chip center temperature may be only 61 degrees.
From the above data, it can be seen that what kind of packaging process is selected for the LED white light, which directly determines the light attenuation of the LED lamp.
Secondly, LED lamp bead working environment temperature.
According to the aging data of a single LED white light, if only one LED white light is on and works, and its ambient temperature is 30 degrees, then the temperature of the bracket when a single LED white light works will not exceed 45 degrees. At this time, the life of this led will be ideal.
If there are 100 LED white lights working at the same time and the interval between them is only 11.4mm, then the bracket temperature of the LED white lights around the light stack may not exceed 45 degrees, but those led white lights in the middle of the light stack may reach 65 degrees high temperature. At this time, it is a test for LED lamp beads. In theory, the light decay of those led white lights gathered in the middle will be faster, and that of the LED white lights around the light stack will be slower.
But if the LED beads are more than 25 mm apart, the heat they radiate from each other will not be so accumulated. At this time, the temperature of each LED white light bracket should be less than 50 degrees, which is more conducive to the normal operation of the LED.
If the LED working environment is in a relatively cold place, the average temperature of the whole year may be only about 15 degrees, or smaller, then the life of the LED is longer.
Or, when the LED is working, there is a small fan nearby to help it dissipate the heat, which is also helpful for the life of the LED.
Anyway, you should know that led is heat resistant. The higher the temperature, the shorter the life of LED. The lower the temperature, the longer the life of LED. The ideal working temperature of LED is between minus 5 and zero. But it's basically impossible.
Therefore, when we understand the ideal working parameters of LED lamp beads, we should try our best to strengthen the heat conduction and dissipation functions when designing lamps. Anyway, the lower the temperature, the longer the LED life.
Thirdly, the working electrical parameters of LED lamp beads are designed.
According to the experimental results, the lower the driving current is, the less heat the LED white lamp emits. Of course, the less brightness it emits. According to the survey, in 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 has a large number of products, such as more than 500, or more, the driving current is generally only 10-15ma, while the driving current of general LED application lighting is only 15-18ma, few people design the current above 20mA.
And the experimental results also show that under the driving current of 14mA, and the air temperature inside reaches 71 degrees, the low-power product will decline to zero in 1000 hours and 3 in 2000 hours, which shows that this low-power LED white light has reached its maximum use in such an environment, which is a kind of damage to it.
Because the aging board has no heat dissipation function, the heat generated when the LED works is basically unable to transmit to the outside. This is proved experimentally. The air temperature inside the aging plate has reached 101 ℃, and the surface temperature of the cover on the aging plate is only 53 ℃, dozens of degrees different. This shows that the plastic cover does not have heat conduction and heat dissipation function basically. But in the design of general lamps, the function of heat conduction and heat dissipation is considered. Therefore, in summary, the design of the 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 very good, it doesn't matter that the driving current of the LED white lamp increases a little, because the heat generated by the LED lamp beads can be exported to the outside in an instant, without damage to the LED, which is the best care for the LED.