Stubby pads for channel cross-talk reduction

Abstract

A metal surface feature, such as a pad, terminating a vertical transition through a substrate, such as an IC package substrate, includes one or more stubs providing high edge surface area to couple with one or more complementary stubs on an adjacent metal surface feature to provide a desired amount of mutual capacitance that may at least partially cancel crosstalk for an overall channel crosstalk (e.g., FEXT) reduction. In embodiments, capacitive coupling of adjacent pads is provided for more than two pads to achieve crosstalk reduction of more than one victim-aggressor pair and/or to achieve crosstalk reduction of more than two aggressors. In embodiments, the pads have a large pitch (e.g., 1000 μm) suitable for interfacing to an interposer or PCB socket, while the gap between the stubs is small (e.g., 15 μm), as limited only by the minimum spacing allowed for metal features on the opposite side of the package employed for interfacing to the IC.