Process for interconnecting conductive substrates using an interposer having conductive plastic filled vias

A method of forming conductive plastic structures in a flip-chip assembly, comprising:

• providing a first substrate with first conductive pads disposed on a surface thereof;
• providing a second substrate with corresponding second conductive pads disposed on a surface thereof;
• providing a preformed planar structure having a first face, a second opposite face, and through holes extending from the first face to the second face, each through hole having an end in each face of the preformed planar structure;
• forcing a conductive plastic material through the through holes from a forcing end of the through holes such that raised globs of the conductive plastic material extend from an opposite end of the through holes;
• removing the conductive plastic material from the face of the preformed planar structure corresponding to the forcing end of the through holes such that the plastic material in the through holes is flush with the forcing ends on the through holes;
• aligning the raised globs with corresponding first conductive pads;
• pressing the first substrate and preformed planar structure together such that the raised globs contact the corresponding first conductive pads and spread to form a liquid seal over the first conductive pads and between the first substrate and the preformed planar structure, and such that raised bumps of conductive material are formed at the forcing ends of the through holes;
• aligning the raised bumps with corresponding second conductive pads;
• and
• pressing the second substrate and preformed planar structure together such that the bumps contact the corresponding second conductive pads and spread to form a liquid seal over the second conductive pads and between the substrate and the preformed planar structure.