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Abstract

A method of fabricating a ball grid array and the array. The method comprises the steps of providing an electrically insulating substrate and forming an essentially gold-free solder ball attach region and wire bond region secured to the substrate. Formation of the solder ball attach and wire bond regions includes forming a layer of electrically conductive material on the substrate, forming a layer of nickel over the layer of electrically conductive material and forming a layer of palladium over the layer of nickel. After chip attach and gold wire bonding or flip chip bonding, solder balls are then applied to the layer of palladium and the solder balls and solder ball attach regions are heated to a temperature sufficiently high and for a sufficient time so that the solder balls extend through and incorporate therein at least a portion of the layer of said palladium and extend to and attach to the layer of nickel. The substrate is preferably one of polyimide or ceramic and the electrically conductive material is preferably copper. The layer of palladium has a thickness of from about 3 to about 10 microinches.

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First Claim