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Printed Circuit Board With Dense Variable Wiring Capacity

IP.com Disclosure Number: IPCOM000100603D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Resavy, JP: AUTHOR

Abstract

Disclosed is a printed circuit board that increases wireability by implementing multiple printed circuit line designs having the same impedance on a single wiring plane.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Printed Circuit Board With Dense Variable Wiring Capacity

       Disclosed is a printed circuit board that increases
wireability by implementing multiple printed circuit line designs
having the same impedance on a single wiring plane.

      High performance printed circuit boards typically utilize a
single impedance design to support circuit requirements.  The signal
I/O count of components supported by these boards is continually
increasing, creating a demand for dense wiring and more board wiring
layers.

      For a single impedance design, present technology only allows
one printed line design to be implemented on each wiring layer of the
printed circuit board.  Since printed lines of varying lengths use
this layer, there is a tendency to design this layer to meet the
electrical design requirements of the expected longest printed
circuit line on that layer.  Consequently, shorter lines will perform
better and exceed the design requirements.

      By designing those shorter lines to occupy only the required
amount of area to meet objectives, it is possible to utilize the
resulting vacated areas on this layer with additional lines, thus
increasing line density on a single layer, reducing the number of
total signal planes needed, and achieving a thinner board which can
meet manufacturing requirements, i.e., drill aspect ratio.

      A constant impedance, multiple printed circuit line design is
achieved by designing both the signal conductor and reference power
plane to have a customized personality which is consistent with the
impedance and noise requirements of the system.

      The design of a typical constant impedance structure is shown
in Fig. 1 and 2.  Here, two d...