This technology means square flat package in Chinese. The pin spacing of the CPU chip realized by this technology is very small and the pins are very thin. Generally, large-scale or very large-scale integrated circuits adopt this packaging form, and the number of pins is generally above 100. This technology is simple to operate and has high reliability when packaging CPU. Moreover, its package size is small, parasitic parameters are reduced, and it is suitable for high frequency applications; This technology is mainly suitable for SMT surface mount technology to install wiring on PCB.