With the rise of new industries such as 5G+8K and XR virtual photography, indoor small pitch LED display has gradually become the first choice for indoor high-end large screen display applications. In order to pursue smaller spacing and better viewing effect, many manufacturers are constantly innovating industrial technical means and seeking better solutions for small spacing.
Nowadays, in the application end field, SMD and COB technologies are "sharing the spring", and each has accumulated a large number of loyal fans. However, in the field of micro pitch LED, due to the limitations of SMD structure, COB is becoming the mainstream technology that major manufacturers are competing to develop.
According to the China LED Small Space Market Analysis Report 2021 released by DISCIEN, the national small space sales will reach 17.15 billion yuan in 2021, of which the share of COB small space segments at P1.6 and below will increase by 3.4% year on year, and the proportion of COB products at P1.1-P1.4 space segments will account for nearly 50%. This means that COB is gradually becoming the optimal solution of LED displays with small spacing, and highlights the huge development space of COB with small spacing.
01.COB vs SMD
SMD, the abbreviation of Surface Mounted Device, refers to packaging materials such as lamp cup, bracket, chip, lead wire and epoxy resin into lamp beads of different specifications, and then welding them on the PCB in the form of a chip to form an LED display module.
SMD display screen generally needs to expose the LED lamp beads, which is not only prone to the problem of cross lighting between pixels, but also poor protection performance, affecting the imaging effect and service life.
COB, the abbreviation of Chip On Board, refers to the LED packaging technology that directly solidifies the LED chip on the printed circuit board (PCB), rather than the formed LED packaging and welding on the PCB.
This packaging method has certain advantages in manufacturing efficiency, imaging quality, protection and application of small micro spacing.
02. Performance PK of both parties
COB packaging technology does not need solder wire, which can completely solve the failure of SMD caused by solder wire factors, greatly reducing the risk of failure caused by metal migration. There is no problem of SMD pad exposure, which can achieve lower failure rate.
SMD packaging technology with formal or vertical structure has a small proportion of light-emitting surface of the chip, and the area of flip COB chip occupies a smaller proportion on the PCB board, without electrode blocking, which improves the luminous rate of the chip. Chips with the same size have higher brightness and smaller chips to achieve ultra-high contrast.
COB packaging can reduce the thermal resistance and solve the heat release problem of sapphire or gallium arsenide substrate; The electrode with larger area is directly connected to the substrate, so that the heat dissipation of electronic components is better, and the color stability and service life of LED display screen are improved.