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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) / 180K

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...