The so-called COB means that the bare chip is adhered to the interconnection substrate with conductive or non-conductive glue, and then wire bonded to achieve its electrical connection. If the bare chip is directly exposed to the air, it will be susceptible to contamination or artificial damage, which will affect or destroy the function of the chip, so the chip and bonding wires are encapsulated with glue. People also call this form of packaging soft packaging.
The bare chip packaged with COB technology has the chip body and I/O terminals above the crystal. During welding, the bare chip is bonded to the PCB with conductive/thermal conductive adhesive. After solidification, the metal wire (Al or Au) is bonded with a Bonder machine. ) are connected to the I/O terminal pads of the chip and the corresponding pads of the PCB under the action of ultrasonic and hot pressure. After passing the test, they are then sealed with resin glue.
Compared with traditional packaging technology, COB technology has the following advantages: low price; space saving; mature process. LED COB packaging technology also has shortcomings, that is, it requires additional welding machines and packaging machines, and sometimes the speed cannot keep up with PCB patching, which has stricter environmental requirements; it cannot be repaired, etc. COB, this traditional packaging technology will play an important role in the packaging of portable products.