多层LCP基板过孔互联结构高精度等效电路模型

High precision equivalent circuit model for via-hole transition structure in multilayer LCP substrate

液晶高分子聚合物(Liquid Crystal Polymer,LCP)作为一种优异的毫米波封装材料,被广泛应用于毫米波高密度系统集成电路设计。在多层电路系统中,过孔作为核心电路单元,可以实现不同层器件以及传输线的互联,有效减小了电路体积,改善了毫米波信号的传输效率。针对传统互联结构建模方法中存在的精度低、耗时长等难题,提出了一种高精度的过孔内在等效电路模型。该模型分析了电源/地平面对过孔传输特性的影响,考虑了电磁模式转换产生的寄生效应,并对传统π型等效电路模型进行了优化。基于过孔的内在等效电路模型,结合微波级联法构建了整个过孔互联结构的等效电路。通过4层LCP封装基板技术,制作了接地共面波导-带状线-接地共面波导(GCPW-SL-GCPW)过孔互联结构电路板并进行测试。结果表明,等效电路仿真结果、全波仿真结果、实测值高度一致,验证了高精度等效电路模型的有效性。

As an excellent millimeter-wave packaging material,Liquid Crystal Polymer(LCP)is widely used in millimeter-wave high-density system integrated circuit design.In multilayer circuit systems,via-holes,as the core circuit units,can realize the interconnection between different layers of devices and transmission lines,which effectively reduces the circuit size and improves the transmission efficiency.In this article,a high-precision intrinsic equivalent circuit model of via-hole was proposed to address the problems of low accuracy and long-time consumption in the traditional interconnection structure modeling methods.The model analyzes the effect of the power/ground plane on the transmission characteristics of the viahole,considers the parasitic effect by electromagnetic mode conversion,and optimizes the traditionalπ-type equivalent circuit model.Based on the intrinsic equivalent circuit model of the via-hole,the equivalent circuit of the via-hole transition structure was constructed by combining the microwave cascade method.By 4-layer LCP package substrate technology,the grounded coplanar waveguide to strip line to grounded coplanar waveguide(GCPW-SL-GCPW)via-hole transition structure circuit boards were fabricated and tested.The results show that the equivalent circuit simulation results,full-wave simulation results,and measured results are highly consistent,verifying the high-precision equivalent circuit model.