高速芯片封装中多平行传输线的设计与优化

随着封装基板朝着高阶高密度方向发展，其信号完整性问题也日趋严重。为研究高速互连结构中反射、串扰等问题与封装基板类型、设计参数和传输线物理特性的相关性，改进了简单的二线平行耦合模型，采用三维电磁仿真软件构建了新的封装级三平行传输线模型，分析了陶瓷基板与有机基板上的传输线反射和串扰特性，研究了该结构下减小反射系数与串扰噪声的方法。仿真结果表明，封装基板上传输线反射系数S11与阻抗匹配程度相关，受信号线宽、厚度和介质厚度影响较大，且S11最小值在不同频率下匹配的最优线宽也不同，需根据不同信号频率具体选择。近端串扰系数受边缘场作用，与线间距密切相关，远端串扰系数受介质厚度影响较大，在相同条件下，远端串扰噪声一般小于近端串扰，对其评估时需结合基板上信号密度、基板材料特性和介质厚度具体分析。

Design and optimization of multiple parallel transmission lines in high-speed chip packaging

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.