Smooth Trenches on Rough Conductor Traces Reduce PCB Insertion Loss
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Solution Overview
Problem
Rough conductor traces on circuit boards lead to increased impedance and reduced electric ion transmission rates due to the skin effect, resulting in higher insertion loss, especially at high frequencies.
Innovation Solution
Constructing smooth trenches on the surface of roughed conductor traces using physical or chemical methods, such as laser treatment, mechanical cutting, or plasma etching, to guide electric ions and reduce surface roughness, thereby enhancing transmission rates and reducing insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If physical or chemical methods are used to roughen the copper foil surface for adhesion, then adhesion between copper foil and dry-film is improved, but surface roughness increases causing increased impedance and reduced electric ion transmission rate
Solution Approach 1:
The invention applies different surface characteristics to different parts of the conductor trace: the majority surface maintains roughness for adhesion, while a central transmission path is smoothed to reduce impedance. This local differentiation allows simultaneous achievement of adhesion and low insertion loss.
Solution Approach 2:
The conductor trace surface is segmented into two functional zones: a rough outer region for adhesion and a smooth central region for electric ion transmission. This segmentation resolves the contradiction by assigning different surface qualities to different functional requirements.
2Strength
If rough conductor traces are used to ensure adhesion, then bonding strength with resin is improved, but insertion loss increases due to extended surface route length
Solution Approach 1:
The conductor trace surface is differentiated into a rough outer region for bonding and a smooth central region for signal transmission. This local quality differentiation allows the rough surface to provide bonding strength while the smooth central path minimizes insertion loss by reducing the effective surface route length.
3Reliability
If smooth trenches are constructed on rough conductor traces to guide electric ions, then electric ion transmission rate is enhanced, but device complexity increases due to additional manufacturing processes
Solution Approach 1:
The invention merges the trench formation process with the existing imaging transfer process by using the same photoresist and etching steps. This integration reduces device complexity by combining multiple functions into a single manufacturing flow rather than adding separate processes.
Solution Approach 2:
The photoresist and etching processes serve dual functions: they define the conductor trace pattern and simultaneously create the smooth central trench. This multi-functionality reduces manufacturing complexity by eliminating the need for separate trench formation 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
The smooth trenches concentrate electron ions on the conductor 'skin', increasing the smooth surface area and reducing impedance, which enhances electric ion transmission rates and minimizes insertion loss while maintaining adequate bonding strength with resin.
Implementation Method 1
The present invention applies the principle of Skin Effect and Hammerstad-Jensen Model due to these electron ions concentrate on skin of conductor traces around in high frequency transmission
Data Source
AI summary
A conductor trace structure reducing insertion loss of circuit board, the circuit board laminates an outer layer circuit board, an inner layer circuit board and a glass fiber resin films which arranged between each board; before laminated process, the conductor traces of the inner layers had formed by etching of imaging transfer process and conductor traces had been roughed process for making the glass fiber resin films having good adhesive performance during laminating; before etching of imaging transfer process that forms the conductor traces of the outer layers or solder resist coat process or coating polymer materials, the conductor traces have been roughed process to make insulating resin layer of the solder resist coat or polymer materials to has better associativity; wherein a smooth trench is formed by physical or chemical process constructed on the roughed conductor traces surface to guide electric ions transmitted on these smooth trench surface to enhance electric ions transmission rate, resulting in reducing the impedance so as to achieve reducing insertion loss.