What are the technical difficulties of LED high-power bead chips?

LED chips are equivalent to the heart of high-power LED bulbs. LED chips are a solid-state semiconductor chip, with one end attached to a bracket, one end being a negative electrode, and the other end connected to the positive electrode of the power supply, making the entire chip encapsulated in epoxy resin. A complete packaging process can ensure the normal use of high-power LED beads. However, in practical use, LED high-power chips also face the following difficulties:

 

1. Uneven current diffusion

For high-power LED chips, a large current drive (usually 350mA) is required. In order to achieve uniform current diffusion, a reasonable electrode structure needs to be designed to ensure uniform distribution of current at the P-type layer. Due to the large chip size and the difficulty of uniform diffusion of current at the P-type layer, high-power LED chips accumulate current below the electrode, resulting in current crowding effect. Due to the current accumulation effect, which means that the current is mainly concentrated in the area directly below the electrode, with relatively small lateral expansion and uneven current distribution, resulting in excessive local current density.

 

2. Low luminous efficiency

Although the packaged white LED output efficiency produced by various manufacturers has reached over 100lm/w, its output efficiency is still very low compared to small-sized LED chips. Due to the large size of large-sized LED chips, when light propagates within the device, the path through which it passes is longer than that of small-sized chips, resulting in a higher probability of absorption of light by the device material. A large amount of light is limited within the device and cannot be emitted, resulting in lower light output efficiency.

 

3. Unstable photoelectric characteristics

Due to the low light output efficiency of high-power LED chip devices, a large amount of light is absorbed inside the device. These absorbed light is converted into heat energy inside the device, causing an increase in the junction temperature of the LED chip. The increase in junction temperature not only causes light attenuation, but also seriously affects the lifespan of the LED chip. At the same time, an increase in temperature can cause the blue light peak of the chip to shift towards the long wavelength direction (i.e., red shift), The mismatch between the emission wavelength of the chip and the excitation wavelength of the fluorescent powder can also lead to a decrease in color rendering.

 

4. The light efficiency of industrial research is far lower than the level of laboratory research and development

Although the mainstream LED chip manufacturers in the international market have reached a high level of laboratory research and development, the research level of industrialization is still low. The main reason for this is that industrialization not only needs to consider cost requirements, but also takes into account the complexity of production processes and chip yield issues.

 

Although we still face some difficulties in the development of high-power LED beads, the times are advancing and science is advancing. I believe that these are not problems in the end, and LED high-power beads will also develop better and better.