What are COB LED SCREEN and SMD LED SCREEN? What are the advantages and disadvantages of COB and SMD

The so-called COB(Chip on Board) refers to the bare chip directly affixed to the PCB, and then electronically connected with aluminum wire or gold wire, and then sealed after testing.

COB technology should be applied in two aspects: PCB (board) level, component level. Hunan Legida Technology Co., Ltd. adopts the technical route of lens molding to realize on-board packaging of wafer.

It is one of the SMT (Surface Mount Technology) components. The method used to produce SMDS is to mount or place the components directly on the surface of the PCB.

                                                      SMD LED Screen


Advantages of COB:

1. Stability

SMD method adopts lamp bead bracket and epoxy resin, due to the different expansion coefficient. It is easy to cause the bracket and epoxy resin encapsulation shell to fall off during reflow welding (240-270 degrees Celsius). 

There is a gap, and gradually dead lamp phenomenon occurs in the later use, resulting in a high defective rate.

COB integrated package does not need to go through reflow lighting, avoiding the problem of gap between lamp holder and epoxy resin caused by high temperature welding in the welding machine.

The phenomenon of dead lamp is not easy to occur after the product leaves the factory. The surface uses lens package, effectively protects the LED chip, and the protection ability is enhanced.

2, excellent heat dissipation

SMD products are mainly heat dissipation through colloids and four pads, the heat dissipation area is small, and the heat will be concentrated in the chip.

That will cause serious light attenuation phenomenon for a long time, and even dead lamp phenomenon, reducing the service life and quality of the display screen.

COB integrated packaging products package the chip on the PCB board, directly through the entire PCB board area for heat dissipation, heat is easy to dissipate, extend the display life.

3. Compression and collision resistance

SMD high-density display uses solder to stick the LED lamp on the lamp board, which is a convex structure, and each lamp has only 4 small pads, which is easy to drop the lamp and die the lamp because of extrusion, touch and other reasons.

COB integrated package the LED chip is packaged on the PCB board through solid crystal, and the surface is packaged with lens, which is smooth and smooth, and more crashed-resistant.

4, moisture-proof, dustproof and anti-static performance

The lamp pad of the SMD display screen is bare, which is prone to short circuit between the lamp pad when it encounters water or moisture.

The face mask used is uneven and difficult to clean when it gets dusty; The metal support used is easy to be oxidized;

The bare lamp foot pad is easily affected by static electricity, and the phenomenon of dead lamp appears. Waterproof, moisture-proof, dustproof, anti-static, and anti-oxidation exist.

The COB integrated package display screen adopts panel packaging technology, and has the functions of moisture-proof, dust-proof, and anti-static.

5. Wide perspective

The SMD display reduces the viewing Angle due to the high packaging of the lamp cup, the accuracy error in the mounting process, and the uneven face mask.

The COB small-pitch display integrated package does not require mask protection, and the left and right viewing Angle is increased to 160 degrees.

The SMD discrete device is blocked by the bracket, and the viewing Angle is only 140°

6. Surface light source alleviates granular feeling

The luminous area of SMD products is small, when viewed closely, it gives a strong sense of granularity, and the light output of LED has a very strong directivity, so when the point light source is applied, it has a very harsh glare.

The COB integrated package forms a surface light source, which produces soft light, effectively alleviates the sense of granularity, and reduces the glare and stinging sensation generated when the screen is viewed for a long time.

7, anti-moire processing

SMD adopts the form of particle packaging, and the black filling area is small, which is easy to cause moire phenomenon (water ripple during shooting).

The Wellcome COB is a flat package with an exclusive laser treatment on the surface to effectively reduce the generation of moors.

8, anti-noise lens technology

SMD: Because of the large wavelength span of the selected chip, each pixel of the chip has a small noise phenomenon.

COB: Select the chip with minimal wavelength difference, and use a unique optical lens technology, so that the brightness and color differences between pixels become invisible to the naked eye, completely no picture noise, color more saturated and pure.

9.COB packaging process is mainly used in LED display small pitch.

At present, the application of small-pitch LED display is in a period of rapid growth, and has been widely used in all walks of life.

However, how to choose the right product for the project needs becomes the problem faced by every project designer and technician.

Through the introduction and analysis of the main technical parameters of the small-pitch LED display, this paper puts forward the selection suggestion of the product.

LED screen is a new type of imaging electronic device made of light-emitting diodes arranged in sequence. Because of its high brightness, wide viewing Angle, long life and other characteristics, it is widely used in all kinds of screens and other products.

Small spacing LED display is refers to the LED pixel pitch under P2.5 indoor LED display, mainly including P2.5, P2.0, P1.8, P1.2, P1.5, P0.9 and P0.6 LED display products.

With the improvement of LED display manufacturing technology, the resolution of traditional LED display has been greatly improved.

Small-pitch led displays are widely used in conference venues, command centers, performing arts stages and advertising entertainment

The small-pitch LED display adopts split module assembly with clear, can be expanded indefinitely, and can be spliced arbitrarily.

LED display also has high brightness, high frame rate, no tailing, heavy use cost and low maintenance cost.

10. The main application of COB is in the indoor meeting room

we call it the commercial led display or commercial led tv. Good presentation of the meeting content and process.

You can also apply the COB LED display to the church, we call this LED display thta it is church LED display or church led screen, increase the sense of technology for the church, show the church prayer process, vivid display of the pastor’s speech.

commercial led display


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