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Nonmechanical Connection Technique for High Speed, High Density Integrity Circuit Applications

IP.com Disclosure Number: IPCOM000091377D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

McDowell, JJ: AUTHOR [+2]

Abstract

This technique eliminates mechanical interconnections in high-speed, high-density integrated circuit applications. A previously undesirable intercoupling between lines known as the backward cross-talk signal is utilized.

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Nonmechanical Connection Technique for High Speed, High Density Integrity Circuit Applications

This technique eliminates mechanical interconnections in high-speed, high- density integrated circuit applications. A previously undesirable intercoupling between lines known as the backward cross-talk signal is utilized.

The packaging density of integrated circuit applications is limited by the number of interconnections that must be made. Another serious limitation is the cross talk, line-to-line coupling, which high-speed, high-density circuits inherently produce. For example, 5 mil wide, 90 ohm microstrip lines separated by 17 mils result in near end noise induced on the quiet line of 13%. A mutual inductance between an active and quiet line of approximately 10 to 15 nanohenries/inch is possible if the lines are 5 mils apart and 20 mils above ground potential. The capacitive coupling is relatively high but is only a small fraction of the inductive coupling when using this particular geometry. The backward cross-talk waveform on a heavily loaded, capacitive, quiet line approaches 50% of the magnitude of the input waveform on the active line.

Drawing 1 shows the waveforms for a typical backward and forward cross- talk signal induced on a quiet transmission line. The spacing between lines s = 5 mils, the height above ground potential h = 20 mils, the line width w = 5 mils, the line thickness t = 2.2 mils, and the rise time tr = 2 nanoseconds.

Drawing A is a schematic r...