Design and optimize the high-speed BGA package and PCB differential interconnection structure, focusing on the analysis of the differential wiring method of the package and PCB interconnection area, signal layout method, signal hole/ground hole ratio, wiring layer and via stubs. The specific impact of high-speed differential signal transmission performance and crosstalk.
The full-wave electromagnetic field simulation software CST is used to establish a 3D simulation model. The time-frequency domain simulation verifies that the optimization method can effectively improve high-speed differential signal transmission performance, reduce crosstalk between signals, and achieve better signal isolation.
In recent years, ball grid array (BGA) packages have become a widely used package type for high-speed ICs due to their small size, many pins, signal integrity and good heat dissipation performance.
In order to adapt to high-speed signal transmission, the chip mostly uses differential signal transmission. With the increasing number of chip I/O pins, the pitch of BGA solder joints is getting smaller and smaller, and the parasitic effects produced by the differential interconnect structure composed of solder joints, vias and printed lines will cause attenuation, crosstalk, etc. A series of signal integrity issues pose severe challenges to high-speed interconnection design.
At present, domestic and foreign scholars’ research on board-level signal integrity issues is still mostly focused on the modeling and simulation of horizontal transmission lines or single vias, and the frequencies are mostly within 20 GHz. There is little research on the transmission performance and coupling problems of differential interconnect structures including vias and transmission lines. There are not many techniques to reduce the crosstalk between the package and the vertical vias in the PCB interconnect area.
The article designs and optimizes the high-speed BGA package and PCB differential interconnect structure. Focus on the analysis of the four aspects of improving the differential wiring method, signal layout method, signal hole/ground hole ratio, wiring layer and back drilling on the specific impact of improving high-speed differential signal transmission performance and crosstalk. A 3D simulation model was established using the full-wave electromagnetic field simulation software CST Microwave Studio. The simulation frequency reaches 40 GHz, which verifies the effectiveness of the optimization method in both the time domain and the frequency domain.