The cause of white LED light bead decay is related to many materials, such as LED bead chips, fluorescent powder for white LED beads, LED glue, LED bead brackets, and LED lamp brackets and shells.

1. The influence of chips on the light attenuation of white LED

From the current experimental results, the impact of chips on light attenuation can be divided into two categories: firstly, different materials of chips lead to different attenuation. Currently, the commonly used substrate materials for blue light chips are silicon carbide and sapphire, while silicon carbide is generally designed as a single electrode with good thermal conductivity. Sapphire is generally designed as a dual electrode, which makes it difficult to export heat and has poor thermal conductivity; The second is the size of the chip, and the attenuation difference varies depending on the size of the chip material.

2. The Effect of Fluorescent Powder on the Bead Decay of White LED Lamps

There are various ways to achieve white LED beads, and the most commonly used and mature one is to apply a layer of yellow fluorescent powder on a blue light chip to mix blue and yellow light into white light. Therefore, the material of the fluorescent powder has a significant impact on the attenuation of white LED. The most mainstream fluorescent powders in the market are YAG yttrium aluminum garnet fluorescent powder, silicate fluorescent powder, and nitride fluorescent powder. Compared with blue LED chips, fluorescent powder has the effect of accelerating aging of white LED, and the impact of different manufacturers' fluorescent powder on light aging is also different, which is closely related to the raw material composition of the fluorescent powder.

3. The effect of solid crystal adhesive on the pearl light decay of white LED lamps

The commonly used solid crystal adhesives in the white LED bead packaging industry include epoxy resin insulation adhesive, silicone resin insulation adhesive, and silver adhesive. Each of the three has its own advantages and disadvantages, and should be comprehensively considered when selecting. Epoxy resin insulation adhesive has poor thermal conductivity but high brightness; The thermal conductivity of silicone insulation adhesive is slightly better than that of epoxy resin, with higher brightness. However, due to a certain proportion of silicon component, the residual silicone resin next to the solid chip and the epoxy resin in the fluorescent adhesive will combine to create a barrier phenomenon. After cold and hot impact, it will peel off and cause dead light; The thermal conductivity of silver glue is better than the first two, which can extend the lifespan of LED chips. However, silver glue has a greater absorption of light, resulting in low brightness. For dual electrode blue light wafers, when silver glue is used for crystal solidification, the control of glue amount is also very strict, otherwise short circuits may occur, directly affecting the yield of the product.

4. The effect of brackets on the pearl fading of white LED lamps

LED brackets mainly include copper brackets and iron brackets. The copper bracket has good thermal conductivity and high price. The thermal and conductive properties of iron brackets are relatively poor, making them more prone to rusting, but they are cheap.

Most LEDs on the market use iron brackets. The impact of brackets made of different materials on the performance of LEDs varies, especially in terms of their impact on light attenuation. This is mainly because the thermal conductivity of copper is much better than that of iron. The thermal conductivity of copper is 398W (m.k), while the thermal conductivity of iron is only about 50W (m.k), which is only 1/8 of the former. The thickness of the electroplating layer on the bracket is also closely related. When selecting a bracket, it is also important to pay attention to whether the bowl size of the bracket matches the luminescent chip and mold particles. The quality of its matching directly affects the optical effect of white LED, otherwise it is easy to