Package Substrate Dielectric Weave Layout for Signal Integrity
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Solution Overview
Problem
The signal integrity of high-speed signal transmission lines in package substrates made of PPG material is compromised due to differences in equivalent dielectric constants of dielectric layers when signal transmission lines are oriented at 0° or 90° along the fiberglass weaving direction, causing a 'weaving effect' that affects signal transmission.
Innovation Solution
The solution involves forming a package substrate with two dielectric layers of different fiberglass widths, where the weaving direction of the fiberglass in one layer is rotated 90° relative to the other, and both layers are laminated together with epoxy resin, allowing for improved signal integrity and heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If signal transmission lines are oriented at 0° or 90° along the fiberglass weaving direction, then manufacturing is simplified, but signal integrity deteriorates due to different equivalent dielectric constants causing weaving effect
Solution Approach 1:
The patent applies asymmetry by using fiberglass fabrics with different weave orientations (0°/90° vs. 45°/-45°) in different dielectric layers. This asymmetric configuration ensures that signal transmission lines never align with the weaving direction of any fiberglass layer, eliminating the weaving effect while maintaining manufacturing feasibility through standardized lamination processes.
2Productivity
If fiberglass width is reduced to accommodate narrower signal transmission lines, then signal line density increases, but dielectric constant uniformity deteriorates causing weaving effect
Solution Approach 1:
The patent solves the problem by transitioning from a single-dimensional consideration (fiberglass width only) to a two-dimensional solution (fiberglass width combined with weave orientation angle). By rotating the weave orientation to 45°/-45° in certain layers, the patent creates a configuration where signal lines pass between fiberglass bundles rather than along them, maintaining dielectric uniformity even with narrow signal lines and high density.
3Temperature
If fiberglass bundles are made wider to improve heat distribution, then heat conduction improves, but signal transmission line coverage decreases
Solution Approach 1:
The patent applies local quality by differentiating the fiberglass configuration in different spatial locations and layers. Specific layers use 0°/90° weave for optimal heat conduction in those regions, while other layers use 45°/-45° weave to prevent weaving effect. This localized optimization allows the system to achieve both good heat distribution and signal integrity simultaneously through layer-specific material properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the covered area by fiberglass, enhances signal transmission line integrity, and ensures more uniform heat distribution, reducing warpage and improving the overall performance of the package substrate.
Implementation Method 1
its dielectric layer is based on woven fiberglass and formed by wrapping the woven fiberglass with epoxy resin
Data Source
AI summary
A manufacturing method for a package substrate, the method including: forming a package substrate by a first dielectric layer formed by weaving at least fiberglass of a first width and a second dielectric layer formed by weaving at least fiberglass of a second width. The second width is different from the first width, and the weaving direction of the fiberglass in the first dielectric layer is 90° relative to the weaving direction of the fiberglass in the second dielectric layer.