Importance

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Abstract

An array of termination resistors has symmetrical geometry producing essentially no net magnetic field and a resultant low inductance is fabricated on a substrate as disk resistors. Conductive through vias are formed in the substrate in an array pattern defining what will be resistor first and second contacts. Each disk resistor has one first contact located at the resistor disk center, and preferably four second contacts located symmetrically about the resistor disk and shared by four adjacent disk resistors. For each resistor, a annular-shaped disk of resistive material is fabricated on a first surface of the substrate, such that a central opening in the disk overlies at least the upper surface of a first contact via. The disk geometry and material determines its resistance. Next, a layer of conductive material is formed over the first surface of the substrate to cover at least the periphery of each disk, and to fill the central opening in each disk. This conductive material electrically couples at least the periphery of each resistive disk with each second contact via to define V.sub.T nodes, and also separately electrically couples the disk center to the underlying first contact via. Solder balls at the lower surface of each via provide an array of first and second contacts for each resistor for attaching the substrate to a printed wiring board or other substrate. An array may include hundreds of termination resistors having substantially real impedances in the range of 50 .OMEGA. to 100 .OMEGA. at frequencies up to about 12 GHz.

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First Claim