Importance

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Abstract

A method of creating high density interlayer interconnects on circuit carrying substrates. A circuit pattern (20) is formed on one side of a substrate (10), and gold balls (30) are selectively placed on the circuit pattern using a thermosonic ball bonder. A liquid solution of a polymer is cast directly on the substrate and the etched circuit pattern such that only the upper portion of each gold ball is revealed when the liquid polymer solution is then dried and cured to form a dry film (40). A second layer of metal is then deposited directly on the dry film, such that it is electrically and mechanically connected to the exposed top of the gold balls. A second circuit pattern (50) is then formed in the second layer of metal. The resulting high density interconnect has two circuit layers separated by a dielectric layer. Each circuit layer is connected to the other by the gold balls that serve as conductive vias.

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First Claim