Ultra high-frequency characterization of high-density 3D module

Signal integrity issues are a great concern in electronic design when higher clock frequencies and higher transmission data rates are needed. Reduced line width, flip chip (FC) technology, and chip scale packaging (CSP) increase wiring density on a circuit board. All available space on a two-dimensional (2D) circuit board is already intelligently used and designers have to find other possibilities to answer market needs. With three-dimensional (3D) packaging technology it is possible to achieve a much smaller package size and weight and a higher integration rate than with planar technology. Increased frequency and shorter distances force us to take into account parasitic effects and interconnections when we design a high-performance device. Parasitic components may cause reflection, distortion, and signal delays. Therefore, accurate models for interconnections, packages, and components are needed for the simulation of applications with high performance. This paper focuses on electrical characterization of vertical interconnection in a stacked 3D structure. High-frequency response of the vertical interconnection is studied with 3D full-wave software. A high-frequency test module was manufactured and measured. The correlation between simulations and experimental results is analyzed. Finally, we propose an equivalent circuit model for the solder-plated polymer ball used in vertical interconnection.