Tapered Wideband Microstrip PCB Structure for Impedance Control
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Solution Overview
Problem
Current PCB manufacturing techniques using FR-4 substrates at high frequencies result in signal reflections, resonance, and radiation due to changes in characteristic impedance, leading to signal transmission losses, and existing solutions either require expensive materials or suffer from transmission losses caused by structural changes.
Innovation Solution
A PCB structure with a substrate that tapers linearly in width and thickness, accompanied by a slanted ground plane, to maintain constant impedance and reduce radiation and resonance, utilizing 3D printing to tailor the substrate and ground plane geometry, ensuring controlled impedance across transmission lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If FR-4 substrate is used at high frequencies with wide conducting strips, then cost is reduced, but characteristic impedance changes due to tapering, causing signal reflections and bandwidth restriction
Solution Approach 1:
The patent changes the geometric parameters of the microstrip transmission line by implementing a tapered width design where the conducting strip width varies along its length. This parameter change allows the line to maintain controlled impedance at high frequencies while using cost-effective FR-4 substrate material, resolving the contradiction between manufacturing cost and signal transmission quality
Solution Approach 2:
The patent applies local quality by creating different regions of the conducting strip with different widths - wider at certain sections and narrower at others. This local variation in geometry allows the transmission line to adapt its characteristic impedance locally to maintain signal integrity across different frequency ranges, thereby improving reliability without increasing overall manufacturing cost
2Ease of operation
If conducting strips are tapered in proximity of PCB die, then physical connection with die is enabled, but characteristic impedance changes drastically, leading to high reflections and bandwidth restriction
Solution Approach 1:
The patent implements a dynamic geometry design where the conducting strip width is not uniform but varies along its length. This dynamic tapering allows the transmission line to physically connect with the PCB die while maintaining controlled impedance characteristics, thereby enabling both physical connection capability and high data transfer rates without the drastic impedance changes that would otherwise occur
3Reliability
If specialized RF packages and high permittivity substrate materials are used, then signal reflections and resonance are reduced, but manufacturing cost increases significantly
Solution Approach 1:
The patent changes the geometric parameters of the transmission line structure, specifically implementing tapered and varied width designs in the conducting strips. These parameter changes compensate for the lower quality of FR-4 substrate material, achieving reduced signal reflections and resonance effects without requiring expensive specialized RF packages or high permittivity substrates, thereby maintaining signal transmission quality while keeping manufacturing costs low
4Area of moving object
If substrate thickness is changed by introducing second conducting plane, then narrower transmission lines are achieved, but transmission losses increase due to resonances and radiation
Solution Approach 1:
The patent solves the problem by transitioning from a two-dimensional planar design to a three-dimensional tapered structure. By varying the width of conducting strips along their length rather than maintaining uniform width, the patent achieves narrow transmission lines where needed while avoiding the transmission losses associated with abrupt thickness changes and multiple conducting planes, thus reducing resonances and radiation
Data Source
AI summary
There is provided a printed circuit board structure, a dielectric substrate structure and a method of manufacturing thereof using wideband microstrip lines for reducing signal reflection, resonance and radiation for maintaining signal quality. The widths of certain portions of the wideband microstrips and underlying substrate portions are tapered gradually for achieving a reduction in a signal reflection, resonance and radiation therefore resulting in maintaining signal quality.