LED display packaging technologies: SMD, COB, GOB, and MIP

SMD: An abbreviation for Surface Mounted Devices. LED products using SMD (Surface Mount Device) packaging encapsulate materials such as lamp cups, brackets, chips, leads, and epoxy resin into LED beads of different specifications. High-speed placement machines use high-temperature reflow to solder the LED beads onto circuit boards, creating display units with varying pitches.

SMD (Surface Mount Device) typically exposes the LED chips or uses a mask. Due to its mature and stable technology, low manufacturing cost, good heat dissipation, and convenient maintenance, it occupies a large share of the LED application market.

SMD LEDs also have some drawbacks: low protection level; frequent problems include LEDs not lighting up, LEDs failing to light up, LEDs malfunctioning, LEDs falling off, and susceptibility to cold air, moisture, dust, and scratches. They lack moisture-proof, waterproof, dustproof, shockproof, and impact-proof properties. In humid climates, large numbers of LEDs are prone to malfunctioning or falling off. During transportation, LEDs are also susceptible to falling off or malfunctioning. They are also easily affected by static electricity, causing LEDs to malfunction.

GOB stands for Glue on Board, a technology designed to solve LED protection issues. It utilizes an advanced new transparent material to encapsulate the substrate and its LED packaging units, forming effective protection. This material not only possesses extremely high transparency but also excellent thermal conductivity. This allows GOB's small-pitch LEDs to adapt to any harsh environment. Compared to traditional SMD, it offers superior protection: moisture-proof, waterproof, dustproof, impact-proof, bump-proof, anti-static, salt spray-proof, oxidation-proof, blue light-proof, and vibration-proof. It can be applied to more demanding environments, preventing large-area LED failures and light drops.

COB: Chip on Board. The light-emitting chip is packaged on a substrate.

COB refers to covering the silicon wafer mounting points on the substrate surface with thermally conductive epoxy resin, then directly placing the silicon wafer on the substrate surface. Heat treatment is performed until the silicon wafer is firmly fixed to the substrate, and then wire bonding is used to directly establish an electrical connection between the silicon wafer and the substrate. There are two main forms of bare chip technology: COB technology and flip chip technology. In chip-on-board (COB), semiconductor chips are directly mounted on a printed circuit board. The electrical connection between the chip and the substrate is achieved using wire bonding, and resin is used to cover the chip to ensure reliability. Although COB is a simple bare chip mounting technology, its packaging density is far lower than that of flip chip bonding technology.

1. Impact and shock resistant;
2. Anti-oxidation and anti-static;
3. Moisture-proof, dust-proof, front-side waterproof, and easy to clean;
4. From point light source to surface light source, eliminating pixelation, resulting in a softer image and less eye strain;
5. Effectively suppresses moiré patterns, reduces light refraction, and provides a superior display;
6. Reduced manufacturing steps, improved quality control, high reliability, and low failure rate;
7. Smaller pixel pitch: COB packaging eliminates surface mount technology (SMT) and other similar processes, allowing for smaller pixel pitches. More pixels per unit result in a clearer and more natural image.

MIP (Mini in Package) is a transitional technology between SMD and COB, it integrates multiple MiniLED chips into a single package (e.g., 4-8 chips in one MIP package) and then mounts them onto a PCB board.

1. Improved display quality: Integrated design reduces the number of individual beads, shrinks the black border area, and reduces moiré patterns compared to SMD, resulting in a less noticeable graininess when viewed at close range (0.5-1 meter);
2. Enhanced maintainability: Supports single-chip replacement (higher maintenance efficiency than SMD, lower cost than COB);
3. Compatibility with small pitches: Enables small pitches from PO.6 to P1.2, balancing display accuracy and production yield;
4. Process compatibility: Utilizes existing SMD mounting production lines, eliminating the need for large-scale equipment modifications and ensuring a smooth supply chain transition.

• Insufficient technological maturity: Compared to SMD and COB, its market application time is shorter, and the supply chain for high-end solutions still needs improvement;
• Higher cost: The integrated packaging process is more complex than SMD, resulting in a higher unit price than SMD products with the same pitch;
• Generally lower heat dissipation: With multiple chips densely arranged within a single package, the heat dissipation efficiency is slightly lower than SMD (PCB heat dissipation design needs optimization).