Printed Circuit Board Wiring Pattern Impedance Reduction
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Solution Overview
Problem
Conventional printed circuit boards in hard disk drives have high characteristic impedances in their wiring patterns, which can lead to increased transmission loss and inefficiency in data transfer between the magnetic head and the magnetic disk.
Innovation Solution
The printed circuit board design rearranges the wiring patterns such that one line is positioned between two others, increasing the opposing surface area and capacitance, thereby reducing characteristic impedances. This is achieved by dividing sections of the wiring patterns and using through holes and connecting layers to ensure electrical connections, allowing for reduced impedance at a lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the wiring patterns are arranged in a conventional configuration, then the structure is simple, but the characteristic impedances are high causing increased transmission loss
Solution Approach 1:
The wiring patterns are divided into multiple lines (first line, second line, third line, fourth line) with specific arrangements. The first and second lines of the first wiring pattern are segmented and arranged between the third and fourth lines of the second wiring pattern, creating a more complex but lower-impedance structure that reduces transmission loss.
Solution Approach 2:
The invention utilizes three-dimensional spatial arrangement by having lines from different wiring patterns interleave with each other. The first wiring pattern lines are positioned between the second wiring pattern lines, effectively using the vertical and lateral dimensions to increase capacitance and reduce characteristic impedance without simply increasing trace width.
2Productivity
If the wiring patterns are rearranged to reduce characteristic impedances, then transmission efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
The wiring patterns are divided into multiple discrete lines that can be manufactured using standard PCB techniques. Each line (first, second, third, fourth) is a separate conductive element that can be traced and connected using conventional manufacturing processes, making the complex arrangement manufacturable.
Solution Approach 2:
An insulating layer is introduced as an intermediary between the first and second wiring patterns. This insulating layer enables the complex interleaved arrangement of lines while maintaining electrical isolation, and it can be applied using standard lamination processes in PCB manufacturing.
3Manufacturing precision
If lines from different wiring patterns are positioned between each other, then capacitance increases and characteristic impedance decreases, but the manufacturing precision requirements increase
Solution Approach 1:
The insulating layer is extracted as a separate functional element between the two wiring patterns. This extracted insulating layer provides the necessary electrical isolation and structural support, allowing the lines to be positioned in the complex interleaved arrangement without direct contact, thereby enabling precise positioning through standard manufacturing tolerances.
Solution Approach 2:
The insulating layer creates equipotential regions between the conductive lines of different wiring patterns. By providing uniform electrical isolation, the insulating layer allows the lines to be positioned close to each other (increasing capacitance) while maintaining controlled impedance, as the electrical field distribution becomes more predictable and manageable.
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
The rearrangement of wiring patterns decreases the characteristic impedances, enhancing data transmission efficiency and reducing transmission loss, ensuring balanced and effective communication between the magnetic head and disk while maintaining a simple and cost-effective configuration.
Implementation Method 1
This increases an area in which the first wiring pattern and the second wiring pattern are opposite to each other, thus increasing capacitances of the first and second wiring patterns. This results in reduced characteristic impedances of the first and second wiring patterns.
Data Source
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AI summary
An end of a first line and an end of a second line of a first write wiring pattern are arranged on both sides of a third line of a second write wiring pattern. Circular connection portions are provided at the ends of the first line and the second line. Through holes are formed in portions of a cover insulating layer above the connection portions, respectively. First connecting layers made of copper, for example, are formed to fill the through holes of the cover insulating layer. A substantially rectangular second connecting layer made of copper, for example, is formed to integrally cover upper ends of the connecting layers. This causes the first and second lines to be electrically connected to each other through the first and second connecting layers.