Product
COB packaging integrates upstream chip technology, midstream packaging technology and downstream display technology. Therefore, COB packaging requires close cooperation between upstream, midstream and downstream enterprises to promote the large-scale application of COB LED displays.
As shown in the picture above, it is a COB integrated package LED display module. The front is an LED light module that forms the pixels, and the bottom is an IC driver component. Finally, the COB display modules are spliced into an LED display of the designed size.
Theoretical advantages of COB:
1. Design and R&D: Without the diameter of a single lamp body, it can theoretically be made smaller;
2. Technical process: Reduce the cost of the bracket and simplify the manufacturing process, reduce the thermal resistance of the chip, and achieve high-density packaging;
3. Engineering installation: From the application side, COB LED display modules can provide simpler and faster installation efficiency for display application manufacturers.
4. Product characteristics:
(1) Ultra-light and thin: According to the actual needs of customers, PCB boards with thicknesses from 0.4-1.2mm can be used to reduce the weight to at least 1/3 of the original traditional products, which can significantly reduce structural, transportation and engineering costs for customers. .
(2) Anti-collision and compression resistance: COB products directly encapsulate the LED chip in the concave lamp position of the PCB board, and then encapsulate and solidify it with epoxy resin glue. The surface of the lamp point is raised into a spherical surface, which is smooth and hard, and is impact-resistant and durable. grind.
(3) Large viewing angle: The viewing angle is greater than 175 degrees, close to 180 degrees, and has a better optical diffuse light effect.
(4) Strong heat dissipation ability: COB products encapsulate the lamp on the PCB board, and quickly transfer the heat of the wick through the copper foil on the PCB board. Moreover, the thickness of the copper foil on the PCB board has strict process requirements, and the thickness of the copper foil on the PCB board is high. Gold craftsmanship will hardly cause serious light attenuation. Therefore, there are very few dead lights, which greatly extends the life of the LED display.
(5) Wear-resistant and easy to clean: the surface is smooth and hard, impact-resistant and wear-resistant; without a mask, it can be cleaned with water or cloth if there is dust.
(6) Excellent all-weather characteristics: It adopts triple protection treatment, with outstanding waterproof, moisture, corrosion, dust, static electricity, oxidation, and ultraviolet effects; it meets all-weather working conditions and can still be used normally in a temperature difference environment of minus 30 degrees to plus 80 degrees.
Current technical difficulties of COB:
1. The one-time pass rate of packaging is not high, the contrast is low, and the maintenance cost is high;
2. Its color uniformity is far inferior to that of a display screen that uses SMD devices that use spectroscopic and color separation.
3. Existing COB packages still use formal chips, which require die bonding and wire bonding processes. Therefore, there are many problems in the wire bonding process and the process difficulty is inversely proportional to the pad area.
4. Manufacturing cost: Due to the high defective rate, the manufacturing cost far exceeds that of SMD small pitch.
Based on the above reasons, although the current COB technology has made certain breakthroughs in the display field, it does not mean the complete withdrawal of SMD technology. In the field where the point pitch is above 1.0mm, SMD packaging technology relies on its mature and stable product performance, wide range Market practice and a complete installation and maintenance guarantee system still play a leading role, and are also the most suitable selection direction for users and the market.
With the gradual improvement of COB product technology and the further evolution of market demand, the large-scale application of COB packaging technology will reflect its technical advantages and value only in the range of 0.5mm~1.0mm point spacing. To borrow a word from an industry insider : "COB packaging is tailor-made for dot pitches of 1.0mm and below."