What is COB? Its full name is chip-on-board, which is chip-on-board packaging. It is a new packaging method that is different from SMD surface mount packaging technology. Specifically, the LED bare chip is adhered to the PCB with conductive or non-conductive glue, and then wire bonded to achieve its electrical connection, and the chip and bonding wires are encapsulated with glue. This packaging method does not eliminate the need for packaging, but it integrates upstream and downstream enterprises. From LED chip packaging to LED display unit module or display screen production, it is all completed in one factory. It integrates and simplifies the production process of packaging enterprises and display screen manufacturing enterprises. The production process is easier to organize and control. The pixel pitch of the product can be smaller, the reliability is doubled, and the cost is closer to civilians.
COB packaging was first used in lighting, and this application has also become a trend. It is understood that COB packaged bulbs have occupied about 40% of the LED bulb market.
As the LED application market gradually matures, users have higher and higher demands for product stability and reliability, especially under the same conditions, requiring products to achieve better energy efficiency indicators, lower power consumption, and more competitive product prices. Based on this, compared with traditional LED SMD chip packaging and high-power packaging, chip-on-board (COB) integrated packaging technology directly packages multiple LED chips on a metal-based printed circuit board. As a lighting module, it directly dissipates heat through the substrate. It not only reduces the manufacturing process and cost of the bracket, but also has the heat dissipation advantage of reducing thermal resistance. Therefore, it has become a packaging method mainly promoted by lighting companies.
In addition to good heat dissipation performance and low cost, COB light sources can also be customized. However, technically speaking, COB packaging still has shortcomings such as light attenuation, short life, and poor reliability. If it can be solved, it will be one of the leading directions for future packaging development.
The application of COB in lighting has become a trend. So, can this packaging technology be applied to display screens? In terms of packaging methods, some companies have made brand-new attempts, and this attempt has been verified and has been promoted and applied in the market. At the same time, it has also attracted widespread attention from people in the industry. So, why does COB display screen get everyone’s attention? There must be a reason.
1. Analysis of the advantages and disadvantages of COB packaging
The application of COB packaging has been used in the lighting field for many years. It has many advantages in all aspects, so it has been favored by many lighting companies. So what kind of sparks will the application of COB packaging technology on the display screen create? Will there be some incompatibility at some levels? Let’s analyze the advantages and disadvantages of COB packaging. It is understood that COB packaging technology has incomparable advantages when applied to display screens.
1. Ultra-light and thin: According to the actual needs of customers, PCB boards with thicknesses from 0.4-1.2mm can be used to reduce the weight to at least 1/3 of the original traditional products, which can significantly reduce structural, transportation and engineering costs for customers.
2. Anti-collision and compression resistance: COB products directly encapsulate the LED chip in the concave lamp position of the PCB board, and then encapsulate and solidify it with epoxy resin glue. The surface of the lamp spot is raised into a spherical surface, which is smooth and hard, and is impact-resistant and wear-resistant.
3. Large viewing angle: COB package uses shallow well spherical luminescence, the viewing angle is greater than 175 degrees, close to 180 degrees, and has a better optical diffuse color muddy effect.
4. Flexibility: Flexibility is a unique feature of COB packaging. The bending of the PCB will not damage the packaged LED chip. Therefore, the COB module can be used to easily produce LED curved screens, circular screens, and wavy screens. It is an ideal base material for personalized styling screens in bars and nightclubs. Seamless splicing can be achieved, the production structure is simple, and the price is much lower than the LED special-shaped screens made of flexible circuit boards and traditional display modules.
5. Strong heat dissipation ability: COB products encapsulate the lamp on the PCB board, and quickly transfer the heat of the wick through the copper foil on the PCB board. Moreover, the thickness of the copper foil on the PCB board has strict process requirements. With the immersion gold process, it is almost
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