With the rapid development of display technology, recently, COB packaging products have become a hot new favorite in the mid-to-high-end display market, and have become the trend of future displays. What is COB? Let the editor give you a detailed introduction today:
LED display technology
At present, there are mainly two packaging technology forms for full-color LED small-pitch displays, one is SMD surface mount component technology, and the other is COB integrated packaging technology. Surface mount components were introduced about twenty years ago. From passive components to active components and integrated circuits, they eventually became surface mount devices (SMD) and can be assembled by pick and place equipment. COB is a brand-new packaging technology that has only been applied to full-color LED screens on a large scale in recent years.
SMD packaging technology
SMD: It is the abbreviation of Surface Mounted Devices, which means: surface mount device, which is one of SMT (Surface Mount Technology) components. At present, indoor full-color LED screens mainly adopt surface-mount three-in-one SMD, which refers to the packaging technology of encapsulating SMT lamps with three different colors of RGB LED chips in the same gel at a certain interval to form a display module.
The main process is to encapsulate the LED light-emitting chip in the bracket to form lamp beads (SMD surface mount parts), and the lamp beads are then attached to the PCB board through soldering. Then put the surface mount parts and PCB board into a high-temperature oven for sintering and solidification (reflow soldering), and then use pressure welding technology to wire the LED, and finally encapsulate the bracket with epoxy resin to form a display module. The modules are then spliced into units.
SMD packaging technology
SMD packaging technology
The core material of SMD process:
Bracket: Conduction, support and heat dissipation. Most of the bracket material is formed by electroplating, consisting of five layers of material, copper, nickel, copper, and silver from the inside to the outside.
LED chip: The chip is the main component of the LED Lamp, and it is a light-emitting semiconductor material.
Conductive wire: connect the chip PAD (pad) and the bracket, and make it conductive.
Epoxy resin: protects the internal structure of the lamp bead, and can slightly change the light-emitting color, brightness and angle of the lamp bead;
COB packaging technology
COB: is the abbreviation of Chip On Board. Means: Chip-on-board packaging technology; that is, a semiconductor packaging process in which the chip is adhered to the interconnect substrate with conductive or non-conductive glue, and then wire-bonded to achieve its electrical connection. To put it simply, the light-emitting chip is directly mounted on the PCB board without the need for brackets and solder feet. Compared with the traditional SMD approach, COB packaging omits the two major processes of making LED chips into lamp beads and reflow soldering. Basically, the chip is directly assembled to the PCB without the limitation of the size of the packaged device, and a smaller dot pitch arrangement can be realized. The current Micro LED adopts COB technology.
COB packaging technology
Compared with other packaging technology steps, the process of COB technology is much simplified and relatively simple, as shown in the figure below:
COB packaging technology
LED screen features of COB packaging technology:
1. Super "stability": almost no faults and no dead spots.
2. Not "dazzling": use surface light sources instead of "dazzling" point light sources and other environmental protection technologies. The brightness is soft and protects human eyes.
3. Not "squeaky": not afraid of bumps, can be wiped with water, protection grade IP66.
4. No "seam": you can "customize" precision displays of different scales.
5. Use "long life": 24 hours and 365 days of continuous use for more than 8 years (theoretical 10 years).
6. "It is the future": It will replace DLP, LCD, plasma, projection, movie screen, SMD LED display and other display products.
The distribution of physical spacing corresponding to different packaging processes of LED display
The distribution of physical spacing corresponding to different packaging processes of LED display
In the future, the mainstream display technology micro-pitch Micro-LED, the micro-pitch can be infinitely small in theory, and it is a fine-pitch display technology based on COB packaging.
