COB (Chip On Board) refers to attaching a bare chip directly to a PCB circuit board, and then using aluminum or gold wires for electronic connection and sealing after testing. COB technology should be applied in two aspects: PCB (board) level and component level. Component-level COB applications are mainly used in IC manufacturing and packaging plants. The process technology is complex and the requirements are strict. This section introduces the PCB-level COB as shown.
COB is mainly used in low-end products, such as electronic toys, calculators, controllers, etc.
The main advantage of the COB process is that it reduces the cost of the product.
The main disadvantages of the COB process:
① Poor reliability of PCB assembly
② The process is complicated
③ The requirements on environment and ESD are high.
The COB process requires higher environmental conditions (100000-level purification environment) and antistatic requirements, which are much stricter than SMT.
First, the general process of COB
Clean the substrate → Dispensing → Chip → Adhesive → Which Wire (Wire Bonding) → Part Line Inspection → Function before Packaging
Test → Encapsulation → Baking → Functional Test after Encapsulation.
COB main equipment
① Wire binding machine, also known as automatic wire welding machine, is used for wire binding (automatic interconnection and joint, also called automatic wire welding).
② Dispenser. Dispensers are the same as those used for underfill and PCB assembly processing components.
③ Oven (with blower). The main function of the blast oven is to cure the dried gum.
④ tensile tester. The main function of the tensile tester is to test the tensile force of the binding wire.
Fastpcba Co., Ltd. has been engaged in one-stop service for automotive electronics PCBA, medical electronics PCBA, military industry, smart home and other fields for many years. It has not made COB products. Today I will share with you the technology of COB mainly because The customer asked some questions about COB, so here I will share the relevant knowledge with you.