Importance

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Abstract

A method for the direct attachment of semiconductor chips to a substrate or module with a polymer interposer. Initially, an interposer sheet is fabricated, which is to be positioned between the chips and the substrate, with via patterns conforming to the contact patterns of the chips. The interposer sheet comprises a sheet of dielectric thermoplastic material selected from an elastomer, a filled elastomer, a polymer, or a copolymer. The chips are then placed on the interposer sheet with each chip being positioned on a conforming via pattern, and the chips are attached to the interposer sheet, as with a suitable adhesive. The vias are then filled with a conductive attachment material comprising a solution of a themoplastic polymer, preferably a copolymer of polyimide and siloxane, and a fine metal, preferably gold, forming a paste. The interposer sheet with the attached chips is then diced into individual chips, with each chip having a section of the interposer sheet attached thereto. The chips with attached interposer are then directly attached to a substrate or module, with the interposer therebetween, by applying heat and pressure, and the substrate provides a controlled joint height and encapsulated joints.

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First Claim