What are the pros and cons of COB LED Screen?

COB LED Screen packaging technology has great advantages compared with SMD packaging technology.

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Its pros: smaller space of LED beads, better protection performance, long service life, and low dead light rate.

Its cons: difficulty in manufacturing finished products, maintenance inconvenience.

The so-called COB package, that is, the chip-on-board package, is actually a kind of LED chip pasted on the PCB substrate, is a new packaging technology different from SMD packaging technology, this packaging technology simplifies the entire packaging process of the chip, but also eliminates the original support and reflow process so that the entire LED is more stable, the point spacing is also smaller, directly improve the resolution of the LED display.

Advantage Analysis

• The distance between points can be smaller

The most important feature of COB packaging technology is that it can reduce the spacing of LED beads. The original package of SMD in the LED display of the small point spacing can only be P1.2, that is, 1.2mm, difficult to achieve, and can not guarantee a certain dead light rate. However, because the encapsulated COB changes the layout and composition of the LED beads, it can essentially reduce the reverse dot pitch, and the resolution is close to the level of the LCD splicing screen.

• Better protection performance

For LED display with small space, during transportation and installation, as long as it is subjected to external force, some light beads will fall off, resulting in dead lights of individual pixels, not emitting light or only showing monochrome, which has some reason with the encapsulation technology. As the encapsulation COB is the LED chip directly encapsulated in the recess of the PCB lamp, and then fixed with epoxy resin, so the whole lamp ball is a raised sphere, both smooth and hard, with better protection.

• Long service life and low dead light rate

COB package product is to encapsulate the lamp on the PCB board, through the PCB board copper foil to quickly transfer the heat of the wick, and the thickness of the PCB board copper foil on the process has strict requirements, coupled with the gold plating process, almost will not cause serious light attenuation. Thus greatly extending the service life of the LED display.

Disadvantage Analysis

• Difficulty in manufacturing finished products

When the LED display is encapsulated in COB, it has to ensure the lamp with no problem before refilling. It cannot replace a single bulb as an SMD package, so it is very demanding throughout the packaging process.

• Maintenance inconvenience

If it&#;s a traditional LED light package SMD, you can disassemble the unit board after a single bulb soldering repair. When it comes to the COB product, the maintenance will affect the surrounding lamps, maintenance is very difficult, and although its protection performance is better, there still will be a certain dead light rate, in this case, can only replace the unit board.

With the introduction of any packaging technology, there are reasons for its existence and space, of course, there will be imperfections. In the future, the development and promotion of technology will also reduce this impact. In short, COB LED screen technology is a future development trend, especially since its LED packaging space is small, for many users, the resolution is a very important technology.

What are CoB LEDs?

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A CoB LED (or chip-on-board LED) is a single device with many LED chips mounted on a thermally efficient substrate placed below a uniform phosphor coating.

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Anyone who walks through a store or home with recessed or track lighting likely experiences light from a chip-on-board LED (CoB). CoBs are widely used because they emit a bright white light output from a compact light source and are very efficient in a broad range of applications.

So what is a CoB LED, and how is it different from other types of LEDs?

CoB (chip-on-board) refers to the way in which the LED unit is constructed. The basic elements of white CoB LEDs are:

• An electrical power supply to provide the energy to drive the LED
• The light-emitting chip or &#;die&#;. This is sometimes referred to as the blue light pump, and is made of a semiconductor material, indium gallium nitride (InGaN), which emits blue photons when energized
• A phosphor coating which converts the blue light to white. The chemical composition of the phosphor is controlled to produce light of a specific color temperature

CoB LED: Space-Saving Array of Multiple LED Chips

A CoB LED is a single device with many LED chips mounted on a thermally efficient substrate, or board. Each chip is a bare die &#; that is, the chip does not have its own leadframe, phosphor coating or lens. This means that the chips can be mounted extremely closely together on the substrate. The close placement of the LED chips allows for high intensity or light density to be emitted from a smaller area than is possible with single packaged LEDs. The CoB LED manufacturer then applies a uniform phosphor coating to the entire array of chips to convert the blue light to the required white color temperature.

Advantages of a CoB LED

A single CoB LED can contain hundreds of chips forming a dense array. This dense array enables a CoB LED to produce more light output from a smaller area than is generally possible with an array of packaged LEDs.

Using a single LED can result in simpler design and product as well as providing optical advantages for uniform light and efficient optics.

Electrical design is simpler because the CoB LED only requires a single two-wire power supply to the entire array of chips. The positive and negative terminals on a CoB LED are clearly visible in the picture of LUXEON CoB Core Range products above. By contrast, an array of packaged LEDs requires dedicated power supply traces to be routed on the PCB to each LED unit.

Production is simpler because the number of units to be soldered to the board will be lower if a CoB LED is used instead of an array of packaged LEDs.

Optically, a broad range of optics, usually reflectors, can be used with CoBs of different sizes to determine the direction and width of the beam such as with a spot or flood lamp.

Finally, a CoB LED&#;s color is potentially more consistent because a single phosphor coating is applied to the entire array of chips, whereas in an array of packaged LEDs, each LED unit has its own phosphor coating.

An example of CoB LEDs of various sizes is shown below.

If you are looking for more details, kindly visit COB LED Sustainability.

CoB LEDs from Lumileds