Product
Chip on Board (COB) is an advanced technology that directly mounts multiple LED chips on a PCB substrate with good heat dissipation performance to achieve direct heat conduction. COB packaging technology integrates upstream chip technology, midstream packaging technology and downstream display technology. Therefore, in order to promote the widespread application of COB LED display screens, close cooperation between upstream and downstream enterprises in the industry chain is essential. As shown in the figure, this is a COB integrated package LED display module. The front side is composed of LED lamp modules to form pixels, and the bottom is installed with IC driver components. By splicing these COB display modules, an LED display screen of the required size can be formed.
The advantages of COB packaging technology include:
1. Design and development: no longer limited to the diameter of a single lamp body, theoretically, a smaller size design can be achieved.
2. Technical process: reduces the cost of the bracket, simplifies the manufacturing process, reduces the thermal resistance of the chip, and achieves high-density packaging.
3. Engineering installation: From an application perspective, COB LED display modules provide display manufacturers with a simpler and faster installation method.
4. Product features: Ultra-light and thin design, 0.4-1.2mm thick PCB boards can be used according to customer needs, and the weight can be reduced to one-third of traditional products, significantly reducing the cost of structure, transportation and engineering.
- Anti-collision and pressure resistance: COB products directly encapsulate the LED chip in the concave lamp position of the PCB board, and use epoxy resin glue to encapsulate and solidify. The surface is convex into a spherical surface, which is smooth and hard, resistant to impact and wear.
- Large viewing angle: The viewing angle exceeds 175 degrees and is close to 180 degrees, and it also has excellent optical diffuse color effect.
- Strong heat dissipation ability: COB products encapsulate the lamp on the PCB board, quickly conduct heat through copper foil, and the thickness of the copper foil meets strict process standards. With the gold immersion process, it will hardly cause serious light attenuation, thereby reducing the phenomenon of dead lights and extending the service life of the LED display.
- Wear-resistant and easy to clean: The surface is smooth and hard, resistant to impact and wear; without mask design, dust can be easily removed with water or cloth.
- All-weather excellent characteristics: Triple protection treatment is adopted, which has significant effects on waterproof, moisture-proof, anti-corrosion, dust-proof, anti-static, anti-oxidation and anti-ultraviolet; it can adapt to the temperature difference environment of minus 30 degrees to plus 80 degrees to ensure normal operation.
It is precisely because of these advantages that COB packaging technology has attracted much attention in the display field.
However, COB technology still faces some technical challenges and difficulties:
1. The one-time pass rate of packaging is not high, the contrast is low, and the maintenance cost is high.
2. The color uniformity is not as good as the display screen after SMD device patching using spectrophotometry and color separation technology.
3. The existing COB packaging still uses positive chip, which requires solid crystal and wire bonding process. There are many problems in the wire bonding link, and the process difficulty is inversely proportional to the pad area.
4. The manufacturing cost is high. Due to the high defective rate, the manufacturing cost is far higher than that of SMD small-pitch products.
Although COB technology has made certain progress in the display field, it does not mean the complete withdrawal of SMD technology. In the field of dot pitch above 1.0mm, SMD packaging technology is still the dominant choice in the market with its mature and stable product performance, wide market application and perfect installation and maintenance system. With the continuous improvement of COB product technology and the further development of market demand, it is expected that COB packaging technology will show its technical advantages and value in the range of dot pitch from 0.5mm to 1.0mm. As industry insiders said: "COB packaging technology is tailor-made for dot pitch of 1.0mm and below."