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As competition in the field of small-pitch LED applications becomes increasingly fierce, LED screen structures with smaller size, stronger performance and higher reliability are becoming the goal pursued by the small-pitch LED industry. Traditional LED light sources use gold wire connection packaging structure, but this structure is easily affected by external forces and the tension of colloid thermal expansion and contraction, which damages the gold wire and leads to dead light problems. In addition, traditional LED light sources (including COB) have a large luminous surface. When matched with small-angle secondary optical devices, the volume of the lamp will become huge, which is not conducive to the appearance optimization of the lamp structure.
Under this trend, high-density COB with small luminous surface high-intensity beam output characteristics and no gold wire packaging structure has become a dazzling new star among many LED technologies and is unanimously optimistic by the industry. So, in which fields will LED screens using COB packaging technology play an important role? Before that, let's take a look at the characteristics of COB packaging technology.
COB packaging is the abbreviation of Chip On Board in English, which literally means putting the chip on the board. It is a new packaging method that is different from DIP and SMD packaging technology. It has obvious advantages in product stability, luminous effect, durability and energy saving.
The first is stability. The processing technology of traditional surface-mount LED display screens is relatively complicated. During the reflow soldering process, due to the different expansion coefficients of the SMD lamp bead bracket and epoxy resin under high temperature, it is very easy to cause the bracket and epoxy resin package shell to fall off and gaps to appear. In the later use, the phenomenon of dead lights gradually appears, resulting in a high defect rate. The reason why the COB technology display screen is more stable is that it does not need to go through reflow soldering to paste the lamp in the processing technology, which avoids the problem of gaps between the lamp bead bracket and epoxy resin caused by high-temperature soldering in the welding machine. Therefore, COB products are not prone to dead lights after leaving the factory. In addition, COB's unique packaging method also effectively protects the light-emitting diodes and enhances resistance.
The second is the luminous effect. COB products encapsulate the lamp on the PCB board, so the heat is directly dissipated through the PCB board. The heat is easily dissipated and almost no serious light attenuation will be caused, so there are few dead lights, which greatly extends the life of the display screen. The traditional surface-mount LED product chip is fixed in the bowl, not in direct contact with the PCB board. It mainly dissipates heat through the colloid and four pads. The heat dissipation area is small, and the heat will be concentrated on the chip. For a long time, it will cause serious light attenuation, or even dead light phenomenon, which reduces the service life and quality of the display.
Next is durability. The COB process small-pitch LED display has the properties of anti-impact, waterproof and moisture-proof, dustproof, oil-proof, anti-oxidation, and anti-static, so it has the characteristics of wear resistance and easy cleaning. The surface of the lamp point is raised into a spherical surface, which is smooth and hard, resistant to impact and wear; bad points can be repaired point by point; there is no mask, and dust can be cleaned with water or cloth.
Finally, energy saving. The COB display uses large-chip light-emitting diodes to effectively increase the brightness, and the heat dissipation is uniform, the brightness attenuation coefficient is small, and it can maintain good consistency after long-term use. When the technicians used a 480*480mm cabinet and the brightness was 1000nit, the energy consumption of COB-P2.5 and SMD-P2.5 was compared. COB consumed 80.57W and SMD consumed 165.7W. It can be seen that under the premise of emitting the same brightness, COB heat dissipation is smaller and more energy-efficient.
The significant advantages of COB packaging technology in stability, luminous effect, durability, power consumption, etc. have laid the foundation for the rapid promotion of COB packaging in some specific market fields. For example, in the field of radio and television studios, the high filling factor optical design of COB products makes the light uniform and close to the "surface light source", effectively eliminating moiré. Its matte coating technology also significantly improves the contrast, reduces glare and glare, and is not easy to produce visual fatigue. This feature makes COB packaging the best technical route to achieve "visual comfort" and "improved experience effect" of small-pitch LED screens, making the camera system personnel extremely fond of this new technology.
Another example is the command and dispatch center market. There are many kinds of small-pitch LED products on the market, but there are only a handful of high-quality small-pitch LED display products that are truly suitable for high-end fields such as command and dispatch control rooms. First of all, the command and dispatch room generally plays a role in the overall operation and management of the entire enterprise and department, and collects information from related enterprises and various related fields within the department to provide a basis for comprehensive command, management and dispatch for the decision-makers. The stability of the display equipment is crucial. The COB integrated overall process makes it highly stable, easy to maintain and repair, and comfortable to watch, which can play its advantages in this field.