Single lamp bead COB packaging technology
This technology follows the idea of traditional packaging technology and has a lower technical threshold. The entire process route and industrial chain layout have not changed much. The display factory still purchases the COB lamp beads packaged by the packaging factory and then installs them on the LED display panel one by one through the SMD process.
Is limited integration COB packaging technology
In order to improve production efficiency and reduce pixel failure rate, while avoiding significantly increasing the difficulty of packaging technology, some manufacturers have begun to try limited integration COB packaging technology. Display manufacturers no longer purchase single COB lamp beads from packaging factories, but limited integrated packaged COB modules with brackets, and then install these modules on Mustang LED display panels through the SMD screen process.
COB integrated packaging technology
COB integrated packaging technology refers to COB packaging technology with high integration level. Generally, it should have an integration level of at least 0.5k. The current technology has exceeded the 2k integration level. The lamp bead integration of the entire LED display panel is completed in the packaging process, and the SMT process is no longer required. COB packaging technology is classified as a packaging-free or packaging-saving mode. However, this packaging method does not eliminate the packaging process, but eliminates the packaging process. Compared with the patch process, the COB packaging process requires less packaging. Going through several steps saves time and process to a certain extent, and also saves costs to a certain extent. The SMD production process requires die bonding, wire bonding, dispensing, baking, stamping, spectroscopic color separation, taping, patching, etc. Process of the Cob is simplified on this basis. First, the IC is attached to the circuit board. Then the die is solidified, wires are bonded, tested, glue is dispensed, and baked to become the finished product.
Challenges faced by COB packaging
- One-time pass rate of the packaging process
Due to the characteristics of the COB packaging method, the COB packaging must be on a large board. This board can have up to 1024 lights. If a light is damaged by SMD, you only need to replace it. However, the 1024 COB packaging after the lamps are packaged, they need to be tested. Only after all lamps are confirmed to have no problems can they be sealed. How to ensure that the entire board of 1024 lights is completely intact and the first pass rate is a very big challenge.
- First pass rate of finished products
For COB products, the lamp is sealed first. After the lamp is sealed, the IC driver device must undergo a reflow soldering process. How to ensure that the 240-degree high temperature in the furnace will not cause damage to the lamp during the reflow soldering process. This is another big challenge. Compared with SMD, COB saves the reflow process on the lamp surface, but the device surface needs to be reflowed the same as SMD. That is to say, SMD needs to be reflowed twice. Different unfortunately, when outdoorSMD screen is reflow soldered, the temperature in the furnace will cause two kinds of damage to the lamp surface. One is the soldering wire. When temperature is extra high, it’ll expand very quickly and be the cause of filament to break. The second is the soldering wire. The heat in the furnace is quickly transferred to the wick through the four pins of the bracket, which may cause tiny fragmentation damage on the wick. This damage is very fatal and is often difficult to detect, including through aging tests. However, this kind of tiny damage and tiny cracks in the crystal will become prominent after a period of time, causing the bulb to fail. COB is to ensure that when the lamp surface undergoes reflow soldering, the high temperature in the furnace does not cause damage to it and ensures the yield rate, which is also a very important aspect.
- Whole lamp repair
For the COB lamps maintenance, its required well repair and maintenance. The biggest problem with single lamp maintenance is that after repair, a circle will appear around the lamp. When repairing a lamp, the surrounding circle will be smoked by the welding gun, making repairs more difficult.
