LED Knowledge Base: Explore the Causes of LED Light Decay

LED Knowledge Base: Explore the Causes of LED Light Decay

As a new type of green lighting, LED lamps are energy-saving, environmentally friendly, and have a long lifespan, and are highly sought after by our customers. However, the problem of LED light decay is another problem that LED lamps have to face. Uninterrupted light decay has seriously affected the use of LED lamps.

  For now, the light decay of white LEDs on the market may be one of the primary problems for civilian lighting. What causes the light decay of LEDs? Generally speaking, there are two main factors for the light decay of LEDs:

   First, the quality of LED products themselves:

  1. The LED chips used are of poor physique, and the brightness decays quickly.

  2. There are defects in the production process, and the heat dissipation of the LED chip cannot be exported from the PIN pin well, resulting in the high temperature of the LED chip and aggravated chip attenuation.

    Second, the use of conditions:

  1. The LED is driven by constant current, and some LEDs are driven by voltage to make the LED attenuate.

  2. The drive current is greater than the rated drive condition.

In fact, there are many reasons for the light decay of LED products. The most important one is the heat problem. Although many manufacturers do not pay special attention to the heat dissipation problem in the secondary products, the light decay degree of these secondary LED products will be higher than that if they pay attention to heat dissipation for a long time. LED products are higher. The thermal resistance of the LED chip itself, the influence of silver glue, the heat dissipation effect of the substrate, and the colloid and gold wires are also related to light decay.

  Three factors that affect the quality and light decay of LED lamps

   First, what kind of LED white light to choose.

  This is very important, and the quality of LED white light can be said to be a very important factor. For example, the same LED white light, represented by the 14mil white light segment chip of Epistar, is encapsulated with ordinary epoxy resin primer, white light glue and packaging glue. After 1,000 hours, the attenuation data is 70% light decay; if it is packaged with Class D low-fat glue, under the same aging environment, the light decay per 1,000 hours is 45%; if it is packaged with Class C low-fat glue, under the same aging environment , the light decay per thousand hours is 12%; if the B-type low-fat glue is encapsulated, under the same aging environment, the thousand-hour light decay is -3%; if the A-class low-fat glue is in the same aging environment, the thousand-hour light decay The decline is -6%.

  Secondly, the working environment temperature of LED lamp beads.

According to the aging data of a single LED white light, if only one LED white light works, and the ambient temperature is 30 degrees, then the bracket temperature of the single LED white light will not work. over 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 stack may not exceed 45 degrees, but the temperature of the LED white lights in the middle of the stack may not exceed 45 degrees. Those LED white lights have the potential to reach high temperatures of 65 degrees. At this time, the LED lamp bead is a test. Then, those LED white lights gathered in the middle will theoretically have a faster light decay, while the LED white lights around the lamp stack will have a slower light decay.

   Anyway, everyone should know that LEDs are afraid of heat. The higher the temperature, the shorter the LED lifespan, and the lower the temperature, the longer the LED lifespan. The ideal operating temperature of LEDs is of course between minus 5 and zero degrees. But this is basically impossible.

   Therefore, after we understand the ideal working parameters of LED lamp beads, we try our best to strengthen the functions of heat conduction and heat dissipation when designing lamps and lanterns. Anyway, the lower the temperature, the longer the LED life.

   Again, the working electrical parameters of the LED lamp beads are designed.

  According to the experimental results, the lower the driving current of the LED white light, the smaller the heat emitted, and of course, the smaller the brightness. According to the survey, in the design of the LED solar lighting circuit, the driving current of the LED is generally only 5-10mA; for products with a large number of lamp beads, such as more than 500 or more, the driving current is generally only 10-15mA , And the driving current of the general popular LED application lighting is only 15-18mA, and few people design the current to more than 20mA.

The experimental results also show that under the driving current of 14mA, and the cover is not ventilated, the air temperature inside reaches 71 degrees, and the light decay of low-decay products is zero for 1,000 hours and 3% for 2,000 hours. , which means that this low-decay LED white light has reached its maximum limit in such an environment, and no matter how large it is, it is a kind of damage to it.

  Because the aging board used for aging has no heat dissipation function, the heat generated when the LED is working basically cannot 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 dozens of degrees. This shows that the designed plastic cover basically does not have the function of heat conduction and heat dissipation. However, in the design of general lamps and lanterns, the function of heat conduction and heat dissipation is considered. Therefore, to sum up, the design of the working electrical parameters of the LED lamp bead 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 is increased a little, because the LED lamp bead works. 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 better to design the circuit to be smaller so that it puts out less heat.

Benwei Lighting is an LED Tube, LED flood light, LED Panel Light, LED High Bay, LED  manufacturer with 12 years of experience. If you want to purchase a high-quality LED flood light or have a more in-depth understanding of the application of LED flood lights, please contact send us inquiry， our  web: https://www.benweilight.com/.