A new via fence structure for crosstalk reduction in high density stripline packages

Via fences are often placed between stripline conductors to suppress unwanted parallel plate mode coupling. However, if the striplines are too close to a fence, the coupling between the striplines is enhanced rather than reduced. In this paper we analyze the coupling between two striplines separated by a via fence using electromagnetic simulation for various dimensional parameters. Finally, we introduce a new via structure that significantly reduces the unwanted coupling.