Patent ID: 7489518

Claim:
An interposer for a multileveled printed circuit board unit in which conductive bumps are stacked between a printed wiring substrate and a mounted component, comprising: an interposer substrate interposed between stacked conductive bumps, the interposer substrate having upper and lower surfaces; conductive pads formed on the upper surface of the interposer substrate, each of the conductive pads being designed to receive a corresponding one of the stacked conductive bumps at a first level; auxiliary conductive pads formed on the lower surface of the interposer substrate, each of the auxiliary conductive pads being connected to a corresponding one of the conductive pads through a via formed in the interposer substrate, each of the auxiliary conductive pads being designed to receive a corresponding one of the stacked conductive bumps at a second level adjacent to the first level; and a conductive wiring pattern formed on at least one of the upper and lower surfaces of the interposer substrate so as to establish electric connection between at least two of at least corresponding ones of the conductive pads or auxiliary conductive pads.