PCB Via Dielectric Sidewall Structure for Impedance Control
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Solution Overview
Problem
Existing printed circuit boards (PCBs) face challenges in controlling via impedance effectively, leading to high costs due to the need for expensive materials across the entire board to achieve target impedance, and there is a need for a cost-effective solution.
Innovation Solution
A two-time drilling technology is employed to create a sidewall of dielectric material in PCB vias, allowing for enhanced impedance control by varying the dielectric constant and thickness of the sidewall through multiple drilling operations and subsequent plating with conductive material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If expensive materials are used across the entire PCB board to achieve target impedance, then via impedance control is improved, but material costs increase
Solution Approach 1:
The patent applies local quality by creating a dielectric sidewall structure that is localized only at the via region rather than using expensive impedance control materials across the entire PCB board. The sidewall is formed by drilling a via, filling it with dielectric material, and back-drilling to leave a controlled thickness ring, thereby providing impedance control precisely where needed (at the via) without incurring board-wide material costs.
2Ease of manufacture
If traditional via structures are used without sidewall control, then manufacturing process is simpler, but via impedance cannot be controlled effectively
Solution Approach 1:
The manufacturing process is segmented into distinct stages: initial via drilling, dielectric material filling, and controlled back-drilling to achieve the desired sidewall thickness. This segmentation allows each step to be optimized independently, maintaining manufacturing simplicity while achieving precise impedance control through the controlled formation of the dielectric ring structure.
Solution Approach 2:
The dielectric material is preliminarily filled into the via before the back-drilling step. This preliminary action ensures that the dielectric material is already in place to provide impedance control, and the subsequent back-drilling merely trims excess material to achieve the target sidewall thickness, rather than attempting to build the sidewall through complex additive processes.
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 method enables precise control of via impedance, reducing material costs while maintaining signal integrity and performance, thus optimizing PCB design without increasing overall expenses.
Implementation Method 1
the via is plated with a conductive material
Data Source
AI summary
A printed circuit board, comprising a first conductive layer and a second conductive layer separated by an insulating layer and a via extending through the insulating layer and electrically coupling the first conductive layer and the second conductive layer. The via includes a sidewall of a dielectric material. In addition, the via is plated with a conductive material.