Abstract: With the development of packaging substrates in the direction of high-end and high-density, the signal integrity problem caused by the increase in signal density on the substrates have become increasingly serious. In order to study the relevance of reflection, crosstalk and other issues in high-speed interconnect structures with package substrate types, and design parameters and physical characteristics of transmission lines, this paper improves the simple two-wire parallel coupling model, uses three- dimensional electromagnetic simulation software to construct a new package-level three parallel transmission line model, analyzes the transmission line reflection and crosstalk characteristics of the organic substrate and the ceramic substrate, and studies the method of reducing the reflection coefficient and crosstalk noise under this structure. The simulation results show that the reflection coefficient S11 of the transmission line on the package substrate is related to the degree of impedance matching, and is greatly affected by the signal line width, thickness, and medium thickness. The optimal line width of the S11 minimum value is also different at different frequencies, and needs to be selected according to different signal frequencies. The near-end crosstalk coefficient is affected by the fringe field and is closely related to the line spacing. The far-end crosstalk coefficient is greatly affected by the thickness of the medium. Under the same conditions, the far-end crosstalk noise is generally less than the near-end crosstalk noise. The evaluation should be based on the signal desnsity on the substrate, substrate material properties, and media thickness.

Key words: package, substrate, transmission line, reflection, crosstalk