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Flip COB is the future of display!

COB led display

1.COB concept

COB, is the abbreviation of Chips on Board in English. This technology originated in the 1960s and is an “electrical design” dedicated to simplifying the packaging structure of ultra-fine electronic components and improving the stability of the final product. Simply put, the structure of the COB package is to directly paste and solder the most primitive, bare chips or electronic components on the circuit board and cover it with a special resin as a whole. Because the bare chip is directly exposed to the air, it is easy to be polluted or artificially damaged, which affects or destroys the function of the chip, so the chip and the bonding wires are sealed with glue.

 

2.Features of COB

1. With ultra-high reliability

COB technology eliminates the process flow of SMD light-emitting tube packaging, color separation, taping, and patching, shortens the process path, and improves the reliability of the product production process. The COB product panel is potted as a whole, which is moisture-resistant, anti-collision, and has a protection level of IP65. There are no exposed pins and anti-static breakdown, which improves the reliability and stability of the display.

2. The welding of COB package uses “low temperature welding process” including hot pressure welding, ultrasonic welding, gold wire welding, etc.

The advantage is that the semiconductor LED crystal particles do not have to withstand high temperatures above 240 degrees. When the surface mount process has dead lights and needs to be repaired, “secondary high temperature reflow soldering” will also occur. The COB process completely eliminates this. This is also the key point that the dead pixel rate of COB process is only one-tenth of surface mount products.

3. Provide a better cooling platform

The amorphous area formed by the package structure can be covered with black light-absorbing material. This makes COB packaged products more excellent in contrast effect and improves the disadvantages of conventional small-pitch LED screens such as sharp pixel grain and glaring brightness.

4. Truly fully sealed structure

The PCB circuit board, crystal particles, solder feet and leads are fully sealed. The advantages of the sealed structure are obvious-for example, moisture resistance, anti-collision, prevention of pollution damage, and easier cleaning of the device surface.

5. COB package can design more unique “display optics” characteristics

The amorphous area formed by the package structure can be covered with black light-absorbing material. This makes COB packaged products more excellent in contrast effect and improves the disadvantages of conventional small-pitch LED screens such as sharp pixel grain and glaring brightness.

6. COB package is suitable for products with small pixel pitch

The COB technology route is not limited by the physical size, bracket, and lead of the SMD LED package, and can break through the SMD pitch limit, achieve higher pixel density, and have a more flexible dot pitch design.

7. COB realizes the conversion from “point” light source to “surface” light source

No pixel graininess; can effectively control the brightness of the pixel center, reduce the intensity of light radiation, inhibit moiré, glare and glare to the retina, suitable for close and long-term viewing, not easy to cause visual fatigue, suitable for close-screen viewing.

3.Formal COB vs. Flip COB

Thanks to the development of small-pitch LEDs, COB, IMD, SMD and other technologies have been prosperous in recent years, and step by step to the forefront of the world. In particular, COB technology differentiates between formal-chip and flip-chip, and the chip size is further miniaturized, and it is believed that flip-chip COB is the future of display!

Formal COB

The small-pitch LED display has always been the main research and development goal of domestic and foreign display companies. Although COB technology has successfully led the development revolution of a new generation of high-definition LED displays, due to the limitations of process technology, the light-emitting angle and wire-bonding distance of the formal COB are The performance development of the product is limited on the route.

Flip COB

With the advent of the 5G era, the market has an urgent need for ultra-high-definition 4K and 8K large-size display applications, and the development of LEDs to micro-pitch displays is an inevitable trend. COB technology continues to heat up with its performance advantages, and the impact of the development of this technology on the industry market pattern has also become the focus of attention in the industry. The birth of flip-chip COB has brought COB technology to a new level.

Advantages of COB flip chip technology

1. Flip chip COB not only saves the wire bonding process, simplifies the production process, but also effectively solves the problems of weak wire bonding and poor wire breakage, as well as the metal migration problem of the formal chip, and the reliability is greatly improved.

2. Chip-level packaging, no physical space for wiring, can achieve higher density.

3. The active layer is closer to the substrate, shortening the heat flow path from the heat source to the substrate, and has a lower thermal resistance.

4. Flip-chip area occupies a smaller proportion on the PCB board, and the substrate duty cycle is increased, with a larger light-emitting area, which can present a darker black field, higher brightness and higher contrast. The luminous efficiency is higher, the surface temperature of the screen is greatly reduced, and the close-range experience is better.

The advantages of flip-chip COB on the basis of formal COB

As an upgraded product of formal COB, flip-chip COB is based on the advantages of formal COB ultra-small dot pitch, high reliability, and non-glaring surface light source.

Further improve the reliability, simplify the production process, better display effect, perfect near-screen experience, and real chip-level spacing can be realized.

Ultra high reliability

The thickness of the encapsulation layer is further reduced, which can completely solve the problem of color lines and bright and dark lines between formal COB modules. 20000:1 ultra-high contrast, 2000CD/㎡ peak brightness, darker black field, brighter brightness and higher contrast. Support HDR digital image technology, static and high dynamic image quality is fine and perfect. The first point-by-point consistent correction technology can achieve precise collection and precise brightness and chromaticity correction functions, with a uniformity of more than 98%.

Large size and wide field of view

2K/4K/8K resolution unlimited size free stitching, suitable for large scene display. It has good viewing angle and side view display uniformity, no color cast under large viewing angles, and a viewing effect of nearly 180 degrees can be achieved.

Ultra-high density, smaller dot pitch

Flip-chip COB is a true chip-scale package, no wire bonding, and the physical space size is only limited by the size of the light-emitting chip. It breaks through the dot pitch limit of the formal chip and is the first choice for products with a dot pitch below 1.0.

Energy-saving and comfortable, good near-screen experience

Full flip-chip light-emitting chip, under the same brightness conditions, power consumption is reduced by 50%. With unique heat dissipation technology, under the same brightness, the surface temperature of the screen is 10℃ lower than that of the conventional LED display with a chip mounted on it, which is more suitable for application scenarios with near-screen experience.

Simplified process, better display

As an upgraded product of formal COB, flip-chip COB further improves reliability based on the advantages of formal COB ultra-small dot pitch, high reliability, and non-glaring surface light source, simplifying the production process, better display effect, and perfect near-screen experience. A true chip-level pitch can be achieved.

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