PCB Via Structure Without Pads for Signal Integrity
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Solution Overview
Problem
Existing printed circuit boards face issues of poor signal transmission integrity and high signal loss due to the connection of metallized through holes with via pads, affecting impedance continuity and signal integrity.
Innovation Solution
The metallized through holes are directly connected to the transmission line without via pads, ensuring impedance continuity and improving signal integrity by removing the via pads in targeted regions identified through signal simulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metallized through holes are connected to transmission lines via via pads, then the connection structure is simpler and easier to manufacture, but impedance continuity deteriorates and signal integrity worsens
Solution Approach 1:
The patent removes the via pad structure from the connection between metallized through holes and transmission lines. By extracting this intermediate component, the invention achieves direct connection where the transmission line directly contacts the metallized through hole wall, eliminating the impedance mismatching and signal loss that via pads cause, while maintaining manufacturing feasibility through direct plating processes.
Solution Approach 2:
The invention merges the functions of the via pad and the metallized through hole into a single integrated structure. The transmission line directly connects to the metallized through hole wall, combining what were previously separate components (via pad + metallized through hole) into a unified impedance-continuous structure, thereby improving signal integrity without adding manufacturing complexity.
2Reliability
If metallized through holes are directly connected to transmission lines, then impedance continuity improves and signal integrity enhances, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the geometric parameters of the metallized through hole, specifically increasing its diameter to provide a larger direct connection area with the transmission line. This parameter modification ensures sufficient electrical contact and impedance continuity without requiring extremely tight manufacturing tolerances, thereby achieving high signal integrity while maintaining reasonable manufacturing precision requirements.
3Loss of energy
If via pads are removed for direct connection, then signal insertion loss reduces and bandwidth increases, but the connection structure becomes more sensitive to manufacturing variations
Solution Approach 1:
The patent applies local quality enhancement by increasing the metallized through hole diameter specifically at the connection region with the transmission line. This localized geometric modification creates a larger contact area that reduces signal insertion loss and provides tolerance to manufacturing variations, making the connection less sensitive while maintaining the benefits of direct connection.
Data Source
AI summary
There are provided an electronic device, a printed circuit board, and a method for preparing a printed circuit board. The printed circuit board includes a layer structure body, a transmission line for transmitting signals, and at least two metallized through holes penetrating through the layer structure body, the transmission line is located in the layer structure body, and has two ends directly connected to walls of two metallized through holes, respectively.