The light decay of LED products is the weakening of the signal in the transmission of light. At the present stage, the LED products produced by global LED manufacturers have different degrees of light decay. High-power LEDs also have light decay, which has a direct relationship with temperature. It is determined by the chip, phosphor powder and packaging technology. At present, the light fade of white LEDs on the market may be one of the top issues for civilian lighting.
2. Two factors affecting LED light decay
1) LED quality issues
The LED chip used is not good, and the brightness is attenuated faster.
There are defects in the production process, and the heat dissipation of the LED chip cannot be well derived from the PIN pin, resulting in an excessive temperature of the LED chip, which intensifies the chip attenuation.
2) Conditions of use
The LED is driven by a constant current, and some of the LEDs are driven by voltage to cause the LED to be attenuated.
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 critical issue is the hot issue. Although many manufacturers do not pay special attention to heat dissipation in secondary products, the long-term use of these secondary LED products will reduce the degree of light attenuation. LED products should be high. The thermal resistance of the LED chip itself, the influence of silver paste, the heat dissipation effect of the substrate, and the colloid and gold wire are also related to light decay.
One of the main problems currently faced by white LEDs is the life problem. Since the price of white LEDs is still very high, if you want to establish a foothold in the lighting market and let users save electricity and save money, they must make up for the long-term and saved electricity bills. The high price of the luminaire. For now, the life of white LEDs makes it difficult to do this.
From the normal use of LEDs, the most important factor affecting the life of LEDs is heat. The source of heat is the Joule heat generated by the normal resistance of the material, the heat generated by the PN junction, the Joule heat generated by the parasitic resistance brought about by the process, and the heat generated by the attraction of the light. The accumulation of heat causes the temperature to rise, and the temperature rise causes the performance of the chip to decline, degenerate, and denature.
