Abstract: A flexible circuit includes a flexible non-conductive substrate having a first surface and a second surface. A first electrically conductive trace is provided on the first surface and a second electrically conductive trace is provided on the second surface. A passage extends through the substrate from an end of the first trace to an end of the second trace. The passage includes a beveled opening of a first size formed in the first side and axially aligned with a second beveled opening of the first size formed in the second side. The first and second openings are interconnected by an aperture axially aligned therewith and being of a second size less than the first size. An electrically conductive surface is provided on the passage for electrically interconnecting the first trace and the second trace.

Abstract: A flexible circuit construction includes a polymeric sheet, via holes in the sheet and metal circuitry disposed on the sheet. The circuitry terminates at a cantilever end partially spanning the via hole to which a solder ball is subsequently attached. The cantilever end allows the solder ball to move relative to the flexible circuit and thus compensate for misalignment and-differential thermal expansion effects.