1.The introduction of the LED

LED display (LED display, LED screen) is composed of LED dot matrix and LED PCB panel. Through the combination of red R, green G, blue B three-color LED lights on and off to display text, pictures, animation, video, and the content , it is an active light-emitting device.It can be divided into three kinds according to the different encapsulation technology: DIP(Double in-line Package ), SMD(Surface Mounted Devices), COB(Chip On Board)

2. The Differences and advantages Between COB and SMD

①The Compression and anti-collision performance

SMD (surface mounted packaging technology) products: The surface mounted LED display is to attach the SMD LED lamp to PCB with solder, which is a raised structure, and each lamp has only 4 very small welding pads, need to be moved during the production and installation. When remove the cabinet , it is easy to drop the lights  or get the dead pixels due to squeezing, touching and other reasons.

COB high-density integrated packaging products: The high-density integrated package LED display directly encapsulates the light-emitting diode chip on the PCB board, and the surface is encapsulated with epoxy resin, which is smooth,flat, more impact-resistant and wear-resistant

②Protection performance

SMD （surface mounted package technology) products: The lamp pin pads of the LED display are exposed, and the problem of the short circuits between the lamp pin pads are prone to occur when exposed to water or moisture; the mask used. It is uneven, and it is difficult to clean up when it is stained with dust; the alloy wires and iron brackets used are easily oxidized; Due to the exposed lamp pin pads,It is easily affected by static electricity, and there are dead lights and blind spots.

COB high-density integrated package products: The high-density integrated package LED display adopts panel package technology, there is no problem of exposed lamp feet, and it is waterproof, moisture-proof, dust-proof, anti-static, anti-oxidation and other functions

③Viewing angle

SMD (surface mount package technology )products: The viewing angle  will be reduced due to the high package of the lamp cup, the error in the accuracy of the lamp patch process, and the unevenness of the mask. The normal viewing angle is only about 120°.

COB high-density integrated packaging products: The high-density integrated package LED display does not require mask protection, and the viewing angle can be increased to more than 160°.

④Stability 

SMD ( surface mounted package technology )products: There are many processing techniques for surface mounted LED display, especially in the process of reflow soldering, due to the different expansion coefficients of SMD lamp bead bracket and silica gel under high temperature (240-270 degrees Celsius), it is very easy to cause bracket and colloid and packaging. The shell falls off and there are gaps. In the later use, dead lights and blind spots gradually appear, resulting in a high failure rate.

COB high-density integrated packaging products：The high-density integrated package LED display does not need to go through the reflow soldering lamp in the processing process, which avoids the high temperature welding in the welding machine.The resulting gap between the lamp bead bracket and the epoxy resin, so the COB product is not easy to appear dead lights and blind spots after leaving the factory.

⑤The heat dissipation

SMD (surface mounted package technology) products: Surface mounted LED products mainly dissipate heat through colloid and four pads. The heat dissipation area is small, and the heat will be more concentrated in the chip, which will cause serious brightness attenuation for a long time, even dead lights and blind spots, which reduces the lifespan of the display screen. and quality.

COB high-density integrated packaging products:The high-density integrated package LED display is to encapsulate the lamp on the PCB board, so the heat dissipation is directly through the PCB board, the heat is easily dissipated, and almost no brightness attenuation is caused, which greatly prolongs the lifespan of the display.