Shenzhen Crescent Optoelectronic Co., Ltd.
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What Are The Difficulties and Advantages & Disadvantages of COB Package LED Display?

A chip on board is a structure in which a plurality of LED chips are directly mounted on a heat dissipation PCB substrate to directly conduct heat.

The cob led package integrates upstream chip technology,  midstream packaging technology and downstream display technology. Therefore, COB packaging requires close cooperation between upstream, middle-stream and downstream companies to promote large-scale application of COB LED displays.

The theoretical advantage of COB

1. Design and development: Without the diameter of a single lamp body, it can be made smaller in theory;

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, the COB LED display module can provide more convenient and quick installation efficiency for the manufacturer of the display application;

4. Product features:

(1) Ultra-thin: According to the actual needs of customers, PCB board with thickness from 0.4~1.2mm can be used to reduce the weight to 1/3 of the original traditional products, which can significantly reduce the structural, transportation and engineering costs for customers.
(2) Anti-collision and compression: COB products directly encapsulate the LED chip in the concave lamp position of the PCB board, and then encapsulate it with epoxy resin. The surface of the lamp point is convex into a spherical surface, smooth and hard, and resistant to impact. mill.
(3) Large viewing angle: The viewing angle is greater than 175 degrees, close to 180 degrees, and has a better optical diffuse color lighting effect.
(4) Strong heat dissipation: COB products are packaged on the PCB board, and the heat of the wick is quickly transmitted through the copper foil on the PCB board, and the thickness of the copper foil of the PCB board has strict technical requirements, plus sinking The gold process hardly causes severe light attenuation. Therefore, there are very few dead lights, which greatly extend the life of the LED display.
(5) Abrasion resistance, easy to clean: the surface is smooth and hard, and it is resistant to collision and wear; there is no mask, dust can be cleaned with water or cloth.
(6) All-weather excellent characteristics: It adopts triple protection treatment, which has outstanding effects of waterproof, moisture, rot, dust, static electricity, oxidation and ultraviolet light; it can meet the all-weather working conditions, and the temperature difference environment from minus 30 degrees to minus 80 degrees can still be used normally.

Current technical challenges of COB

1. The cob led package has a low pass rate, low contrast and high maintenance cost.
2. Its color uniformity is far less than the display screen after the SMD device is used for spectral separation;
3 If you need to increase the serial number, you can directly enter the number 456 blank;
4. Manufacturing costs: due to high defect rate, resulting in manufacturing costs far exceed SMD small spacing.

Based on the above reasons, although the current COB technology has made certain breakthroughs in the display field, it does not mean that the SMD technology has completely withdrawn. In the field of 1.0mm or more point spacing, SMD packaging technology relies on its mature and stable product performance and extensive. The market practice and perfect installation and maintenance guarantee system are still the dominant role, and it is also the most suitable selection direction for users and markets.

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 in the interval of 0.5mm~1.0mm, which is borrowed from the industry. "The COB LED package is tailored to 1.0mm and below."
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