What is a COB package?
Cache on Board (Cache on board) A cache that is integrated on the processor card. It is usually referred to as a secondary cache. For example, the Pentium II COB: (chip On board) is bound. On printed boards, IC suppliers are reducing the yield of QFP (a package of SMT parts) packages for LCD control and related chip production. Therefore, the traditional SMT method is gradually replaced in future products.
What is the difference between COB packaging technology and traditional packaging?
The COB package is a package that directly bonds the LED chip to the PCB board. What is the difference between this packaging method and the traditional SMD LED packaging technology, which is better? What are the advantages and disadvantages of these two packaging methods?
There are two main forms of bare chip technology: one is COB technology and the other is Flip chip.
LED COB packaging technology
The so-called COB is to adhere the bare chip to the interconnect substrate with conductive or non-conductive glue, and then perform wire bonding to realize electrical connection. If the bare chip is directly exposed to the air, it is susceptible to contamination or man-made damage, affecting or destroying the function of the chip, so the chip and the bonding wire are encapsulated by glue. This package is also referred to as a soft encapsulation.
The bare chip packaged by COB technology is the chip body and the I/O terminal above the crystal. When soldering, the bare chip is bonded to the PCB with conductive/thermal adhesive. After solidification, the wire is bonded by a Bonder machine (Al or Au). Under the action of ultrasonic and hot pressing, they are respectively connected to the I/O terminal pad of the chip and the corresponding pad of the PCB. After the test is passed, the resin glue is sealed.
Compared with traditional packaging technology, COB technology has the following advantages: low price; space saving; mature technology. LED COB packaging technology also has shortcomings, that is, it needs to be equipped with another welding machine and packaging machine. Sometimes the speed cannot keep up with the PCB patch, which is more strict on the environment; it cannot be repaired. COB, this traditional packaging technology will play an important role in the packaging of portable products.
LED COB packaging technology common problems
Q: Color temperature shift problem in COB packaging process of LED light source
When the LED light source is packaged in COB, it adopts the traditional high-power packaging process. After baking, it is found that the color temperature is always offset too much. The target color temperature is 6000K, the initial point is 5000K, but the rubber powder is directly baked 10000K, which is the baking of silica gel. The problem of the craft is still not suitable for the rubber powder. Please, please!
A: The baking temperature is too high, the electrode distance becomes too close, and the time for finishing the glue to the baking is shortened. The difference in color temperature should be caused by the precipitation of the phosphor. It is recommended to bake in time and increase the temperature to make it Quickly harden to avoid phosphor precipitation! Review the temperature rise curve of the OVEN box
Q: In the LED packaging technology, what is the difference between the Lamp led packaging technology and the COB package?
Both are in-line rather than patched. What is the difference? Which aspects are they applied to separately? One for high power and one for low power?
A: COB technology is generally suitable for use on a substrate with other electronic components.
LED COB should be a special function module such as flashing function or digital character, color control module if it is made into in-line package. Both large and small power can be used as COB or lamp. There is no difference in this respect.
Q: Will the COB integrated package be used as a planar light source, will it replace the current patch products?
A: There is no substitute. Both are future developments and will coexist for a long time.
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