Flexible Copper-Clad Laminate With Low Insertion Loss and Strong Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing flexible copper-clad laminates (FCCLs) used in high frequency and high speed applications suffer from signal loss due to the skin effect and weakened adhesion strength, leading to reliability issues.
Innovation Solution
A surface-treated copper foil with specific grain size, surface roughness, and surface treatments, combined with a dielectric layer of polymeric material, to enhance conductivity and adhesion, resulting in a flexible copper-clad laminate with improved peel strength and reduced conductor loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the surface roughness of the copper foil is reduced to lower conductor loss, then the adhesion strength of the copper foil to the dielectric layer is weakened
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness of the copper foil within a specific range (Ar ≤ 3.0 μm) and the copper content (99.90-99.99 wt%). This optimization balances the competing requirements: smooth enough surface to reduce conductor loss according to skin effect, but rough enough to maintain adhesion strength with the dielectric layer.
Solution Approach 2:
The patent uses composite materials by combining high-purity copper (99.90-99.99 wt%) with controlled surface treatment to create a copper foil that achieves both low conductor loss and sufficient adhesion. The composite nature is further enhanced by the combination of the copper foil with the dielectric layer, forming a flexible copper-clad laminate with optimized performance characteristics.
2Strength
If non-copper elements such as nickel or silane are added to increase peel strength, then the magnetic permeability and electric resistance increase leading to higher insertion loss
Solution Approach 1:
The patent applies parameter changes by strictly limiting the copper purity to 99.90-99.99 wt% and controlling the surface roughness within specific ranges. This approach achieves sufficient peel strength through optimized physical and chemical parameters of the copper foil itself, eliminating the need to add non-copper elements that would increase magnetic permeability and electric resistance.
Solution Approach 2:
The patent applies the extraction principle by removing non-copper elements from the copper foil composition. Instead of adding nickel or silane to improve peel strength, the invention extracts these problematic elements and achieves the desired adhesion through controlled copper purity and surface treatment, thereby avoiding the harmful effects on magnetic permeability and electric resistance.
3Weight of moving object
If the copper foil thickness is reduced to achieve lighter weight and compactness, then the conductivity and signal transmission performance deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the copper foil thickness to 3-35 μm and controlling the surface roughness (Ar ≤ 3.0 μm) and copper content (99.90-99.99 wt%). This combination of parameters achieves the desired weight reduction while maintaining low conductor loss through the smooth surface that minimizes skin effect losses, allowing thin foils to perform as well as thicker ones.
Solution Approach 2:
The patent applies local quality by focusing on the surface characteristics of the copper foil rather than uniformly increasing the entire foil thickness. By optimizing the surface roughness and copper content locally at the surface where current flows (skin effect region), the patent achieves low signal loss without the need for increased overall thickness, thus maintaining light weight and compactness.
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 solution provides a flexible copper-clad laminate with high peel strength and low conductor loss, enabling high speed and high frequency signal transmission with reduced insertion loss, suitable for applications in electronic devices.
Implementation Method 1
Under the high speed/high frequency conditions, the current of signal transmission is mainly conducted across the surface of copper conductor which is a well-known phenomenon named skin effect.
Implementation Method 2
One approach to lower the conductor loss of FCCL is by reducing the surface roughness of the copper foil considering the skin effect mentioned previously.
Data Source
AI summary
Disclosed are surface-treated copper foils having at least one treated surface that exhibit high conductivity and a set of surface properties. Also provided are flexible copper-clad laminates and printed circuits made therefrom. The present printed circuits exhibit low insertion loss and are suitable for use in high speed/high frequency applications.