Flip chip, also known as Flip chip, depositing of tin in the I/O pad the shot, and then heat the Flip chip using molten tin shot put and the technique combining ceramic substrate to replace conventional lineup, gradually become a mainstream packaging for the future, the current is mainly used in high pulse of CPU and GPU (GraphicProcessor Unit) and Chipset and other products.Compared with COB, the chip packaging format structure and I/O side down (tin) direction, because of I/O terminal are distributed throughout the chip's surface, so the packing density and speed of processing the Flip chip has peaked, in particular, it can be used in a similar way to SMT processing, so is the final direction of chip packaging technology and high density installation.Flip Chip Connection there are three main types of C4 (Controlled Collapse Chip Connection) and DCA (Direct Chip attach) and FCAA (Flip Chip Adhesive Attachement).
C4 is similar to a form of ultra fine pitch BGA solder ball array, which is connected with silicon general spacing is 0.23, and 0.254 mm.Solder ball diameter is 0.102, and 0.127 mm.Solder ball components for 97 pb/sn.The solder ball on the silicon wafer can be complete or partial distribution.
Because ceramic can withstand higher reflow temperature, ceramic is used as base material of C4 connection, usually on the surface of the ceramic prior distribution of Au and Sn plating connection plate, then flip chip connection in the form of C4.The advantages of C4 connection is:
1) has excellent electrical and thermal properties
2) in the case of medium solder ball spacing, the number of I/O can be very high
3) is not restricted by bonding pad size
4) can be suitable for mass production
5) can greatly reduce the size and weight