Controlled impedance structures for high density interconnections

An interconnection device comprising:

• first and second circuit layers, each circuit layer comprising a plurality of conductive circuit paths coupled with a formable insulating layer having a uniform thickness and having first and second surfaces, each conductive circuit path terminating in a fine-pitch terminal at a proximal end and a coarse-pitch terminal at a distal end, wherein each fine-pitch terminal is disposed in a fine-pitch terminal array comprising a plurality of fine-pitch terminals, and each coarse-pitch terminal is disposed in a coarse-pitch terminal array comprising a plurality of coarse-pitch terminals,
• wherein the first circuit layer further comprises a first contiguous metal layer disposed against the second surface of the formable insulating layer,
• wherein the first contiguous metal layer functions as a ground reference layer, and
• wherein the first circuit layer further comprises a second contiguous metal layer separated from the first contiguous metal layer by a dielectric layer of uniform thickness;
• and
• a first insulating adhesive layer disposed between the first and second circuit layers, wherein a section of the first insulating adhesive layer has a non-uniform thickness.