Structure and method of making interconnect element, and multilayer wiring board including the interconnect element

A method of fabricating an interconnect element, comprising:

• fabricating a metal layer overlying a carrier layer, the metal layer including a plurality of metal traces;
• providing a dielectric element to overlie said metal layer and said carrier layer such that outer surfaces of said plurality of metal traces and a first major surface of said dielectric element are adjacent to said carrier layer, and inner surfaces of said plurality of metal traces are disposed within recesses in said dielectric element remote from said outer surfaces, said dielectric element having a second major surface remote from said first major surface;
• providing a plurality of metal posts extending from said inner surfaces of said plurality of metal traces at least to said second major surface of said dielectric element;
• and
• removing said carrier layer to expose said first major surface of said dielectric element and said outer surfaces of said plurality of metal traces.

A method of manufacturing a multilayer wiring board including a plurality of wiring boards, wherein a plurality of interconnection layers, made from metal, are fabricated on one primary surface of an interlayer insulation layer in an embedded state so that a primary surface of said interconnection layers will be coplanar with said one primary surface of said interlayer insulation layer;

• an interlayer contact pillar is fabricated from metal on at least a part of an interconnection layer on the other primary surface of said plurality of interconnection layers, so as to pass through said interlayer insulation layer so as to arrive at, and be exposed at, the other primary surface said interlayer insulation layer;
• and a low melting point metal layer for improving connectivity is fabricated on said exposed surface of said interlayer contact pillar, are prepared;
• and
• said plurality of prepared wiring boards are joined in a stack such that the interlayer insulation layers of adjacent wiring boards will be fused and integrated together, along with the interconnection layer of one wiring board connecting to the interlayer contact pillar of another wiring board, or the interlayer contact pillar of one wiring board being connected to the interlayer contact pillar of another wiring board, through a low melting point metal layer for improving connectivity, when connecting, through said low melting point metal layer for improving connectivity, through applying heat and applying pressure when said prepared plurality of wiring boards are in a state wherein said prepared plurality of wiring boards are aligned so that the interconnection layer of one wiring board contacts the interlayer contact pillar of another wiring board, or the interlayer contact pillar of one wiring board contacts the interlayer contact pillar of another wiring board, through said interlayer contact pillar.