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Method for trace/glass orientation and trace pitch design rules to normalize Dk variations of reinforced material

IP.com Disclosure Number: IPCOM000010417D
Publication Date: 2002-Nov-27
Document File: 6 page(s) / 145K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for trace/glass orientation and trace pitch design rules to normalize dielectric constant (Dk) variations of reinforced material. Benefits include improved performance.

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Method for trace/glass orientation and trace pitch design rules to normalize Dk variations of reinforced material

Disclosed is a method for trace/glass orientation and trace pitch design rules to normalize dielectric constant (Dk) variations of reinforced material. Benefits include improved performance.

Background

              Local Dk variations and impedance (Zo) variations are caused by local glass/resin variations when woven glass fabric is used as material reinforcement. Minimizing Dk solves the issue of Zo variations and reduces timing jitter issues that result from Dk variations.

              A conventional method of reducing Dk variation in glass woven-reinforced PCB laminate materials is to use multiple layers of woven glass fabric in the dielectric and wider traces for the bus design.

              The conventional solution is to place board design/traces at or near parallel or perpendicular angles to the glass fabric weave of the material (see Figures 1 and 2). The traces are not intentionally spaced at the same increments as the glass weave of the dielectric.

General Description

              The disclosed method uses input/output (I/O) routing to average/normalize the dielectric constant variation caused by glass weave topography across lines of bus on reinforced material (see Figure 3).

              The key elements of the method include:

•             I/O routing methodology

•             Dk distortion from line to line removed by I/O trace routing methodology

Advantages

      The disclosed method provides advantages, including:

•             Improved performance due to the normalization of the dielectric...