Small pitch packaging technology， SMD, COB, GOB, which one will become mainstream

Since the development of the LED display industry, a variety of production and packaging processes have emerged one after another. From the previous direct insertion (Lamp) process, to the surface mount (SMD) process, to the emergence of COB packaging technology, and finally to the emergence of GOB packaging technology.

In the development of small pitch manufacturing technology, many small pitch manufacturers have been trying their best to achieve the best solution for small pitch display screens.

SMD surface mount process technology

SMD: It is the abbreviation of Surface Mounted Devices, which means: surface mount devices. LED products encapsulated by SMD (surface mount technology) are lamp cups, brackets, wafers, leads, epoxy resins and other materials encapsulated into lamp beads of different specifications. Use a high-speed placement machine to solder the lamp beads on the circuit board with high-temperature reflow soldering to make display units with different spacings.

SMD small pitch generally exposes the LED lamp beads or uses a mask. Due to the mature and stable technology, low manufacturing cost, good heat dissipation effect, and convenient maintenance, it also occupies a large share in the LED application market. However, due to serious defects, it can no longer meet the needs of the current market.

1. Low protection level: It is not moisture-proof, waterproof, dust-proof, shock-proof, and collision-proof. In humid climates, large batches of dead lights and broken lights are prone to occur. During transportation, it is easy to drop lights and break lights. It is also easy to be affected by static electricity, causing dead lights.

2. Great damage to the eyes: Long-term viewing will cause glare and fatigue, and cannot protect the eyes. In addition, there is a "blue harm" effect. Because the blue LED has a short wavelength and high frequency, the human eye is directly and long-term affected by blue light, which is easy to cause retinal disease.

3. Short life of LED lamps: The performance of the lamp is greatly shortened by environmental factors, and the performance of the PCB is affected by environmental factors. Copper ion migration occurs, resulting in micro-short circuits

4. Mask: When using the small SMD spacing of the mask, it is easy to bulge the mask when used in a high temperature environment, affecting viewing. After a period of use, the mask cannot be cleaned, causing whitening or yellowing on the spot, which is not only ugly in appearance, but also affects viewing.

COB packaging technology

COB packaging stands for Chip on Board packaging, which is a technology to solve the heat dissipation problem of LEDs. Compared with direct plug-in and SMD, it is characterized by saving space, simplifying packaging operations, and having an efficient thermal management method.

It is to adhere the bare chip to the interconnect substrate with conductive or non-conductive glue, and then perform wire bonding to achieve its electrical connection. If the bare chip is directly exposed to the air, it is susceptible to contamination or human damage, affecting or destroying the chip function, so the chip and bonding wires are encapsulated with glue. People also call this packaging form soft encapsulation. It has certain advantages in production efficiency, low thermal resistance, light quality, application, cost, etc.

However, as a new technology, COB has insufficient accumulation in the small-pitch LED industry, process details need to be improved, and the main products in the market are temporarily at a cost disadvantage.

1. Poor consistency: Because there is no first step to select the lamp, it is impossible to separate light and color, and the consistency is poor.

2. Severe modularization: Because it is composed of many small unit boards, the default color is inconsistent and the modularization is serious.

3. Surface flatness: Due to the glue application of a single lamp, the flatness is poor and the surface feels granular

4. Difficulty in maintenance: Due to the need for professional equipment, maintenance is difficult and the maintenance cost is high. Generally, the product needs to be returned to the factory for maintenance.

5. Manufacturing cost: Due to the high defect rate, the manufacturing cost is far higher than that of SMD small pitch

GOB packaging technology

GOB is the abbreviation of Glue on board. It is a packaging technology that is used to solve the protection problem of LED lamps. It uses an advanced new transparent material to encapsulate the substrate and its LED packaging unit to form effective protection. This material not only has ultra-high transparency, but also has super thermal conductivity. GOB small pitch can adapt to any harsh environment and achieve true moisture-proof, waterproof, dust-proof, impact-proof, UV-resistant and other characteristics.

Compared with traditional SMD, it is characterized by high protection, moisture-proof, waterproof, impact-proof, UV-resistant, and can be applied to more harsh environments to avoid large-scale dead lights and falling lights.

Compared with COB, it is easier to maintain, has lower maintenance costs, has a wider viewing angle, and the horizontal and vertical viewing angles can reach 180 degrees. It can solve the problems of COB's inability to mix lights, severe modularization, light separation and color separation, and poor surface flatness.

The production steps of the new GOB series products are roughly divided into 3 steps:

1. Select the best materials, lamp beads, ultra-high brush IC solutions in the industry, and high-quality LED chips

2. After the product is assembled, before GOB glue is poured, age it for 72 hours and test the lamp

3. After GOB glue is poured, age it for another 24 hours to confirm the product quality again

In the competition of small-pitch LED packaging forms, SMD packaging, COB packaging technology, and GOB packaging technology, as for which of the three can win in the competition, it depends on the advancement of technology and the market's acceptance. Who will be the final winner, let us wait and see.