Waveguide substrate and method of making waveguide substrate

Abstract

A waveguide substrate includes a core substrate through which first through holes and second through holes are formed, a first conductive layer covering an inner wall of the first through holes and both sides of the core substrate, a second conductive layer covering an inner wall of the second through holes and both sides of the core substrate, a first filler material filling a space surrounded by the first conductive layer inside the first through holes, a second filler material filling a space surrounded by the second conductive layer inside the second through holes, and third conductive layers disposed on respective sides of the core substrate, the third conductive layers overlapping the first and second through holes in a plan view, and the third conductive layers being electrically connected to the first and second conductive layers, wherein the second conductive layer overlaps the first through holes in the plan view.