Soldered ball and copper interconnect are two main interconnect structures in the flip-chip package. Following the increase of clock frequencies of digital circuits, the differential signal has become the most commonly used in high-speed digital circuit. In the study, the HFSS full-wave simulation method is used to research the high-speed differential signal transmission characteristics of the differential soldered ball and copper interconnect structures in the lfip chip package. First, the differential soldered ball is modeled under ideal circumstances to analyze the impact of differential signal transmission characteristics of the ball size and pitch parameters of soldered ball array. Under the assumption that the ball pitch is twice the size of ball diameter, smaller ball size and pitch could achieve better transmission performance over a wide frequency range when the diameter of the often used ball is between 0.1 mm and 1.27 mm. Second, parallel, inside-non-parallel and outside-non-parallel copper interconnect structures are compared. Parallel copper structure is observed to be better than inside-non-parallel copper structure, and inside-non-parallel copper structure is better than outside-non-parallel copper structure.%焊球与铜互连是芯片倒装封装中两种主要的互连结构，而随着数字电路时钟频率的不断提升，差分信号已成为高速数字电路中最常用的信号形式。采用HFSS全波仿真方法对芯片倒装封装中高速差分信号在差分对焊球和铜互连结构中的传输特性进行了研究。首先在理想情况下对差分对焊球结构进行了建模，分析了焊球阵列中焊球的尺寸和节距参数对差分信号传输特性的影响，发现在假定焊球节距为焊球直径2倍的情况下，现阶段常用的直径为0.1~1.27 mm的焊球中焊球尺寸和节距越小越能在宽频段内实现更好的传输性能。其次对平行式和内弯式、外弯式非平行差分铜互连结构进行了对比研究，发现平行式结构优于内弯式非平行结构，内弯式非平行结构优于外弯式非平行结构。
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