Roughened Copper Foil Electrolytic Process for PCB Adhesion
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Solution Overview
Problem
Existing methods struggle to create a roughening layer on copper foils that balances low roughness with high adhesion, which is crucial for fine lines on printed circuit boards.
Innovation Solution
A manufacturing method for a roughened copper foil involves an electrolytic process using an electrolyte solution with specific concentrations of copper ions, sulfate ions, and a coordination compound, such as benzotriazole-based compounds, to form a roughening layer with low roughness and high adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional electrolytic processes are used to form a roughening layer on copper foil, then adhesion between copper foil and insulating resin can be improved, but surface roughness increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentrations of copper ions (0.1-20 g/L), sulfate ions (30-120 g/L), and coordination compounds (0.1-10 g/L) in the electrolyte solution. By optimizing these chemical parameters and electrolytic conditions (current density 1-120 A/dm², temperature 25-60°C, duration 1-45 seconds), the process forms a roughening layer with controlled surface roughness (Rz ≤ 1.0 μm) while maintaining high adhesion strength (≥ 4.0 lb/in).
Solution Approach 2:
The patent employs composite materials by form a roughening layer composed of copper nodules with specific microstructure. The roughening layer is a composite structure where copper nodules are formed through controlled nucleation and growth in the electrolyte solution, creating a hierarchical microstructure that simultaneously provides mechanical interlocking for adhesion and controlled roughness for fine line applications.
2Manufacturing precision
If the roughening layer is made finer to support fine lines on PCBs, then manufacturing precision is improved, but adhesion strength deteriorates
Solution Approach 1:
The patent resolves this contradiction by implementing a two-stage electrolytic process with different copper ion concentrations. The first stage uses lower copper ion concentration (0.1-10 g/L) to form fine copper nodules with controlled roughness, while the second stage uses higher copper ion concentration (1-20 g/L) to enhance adhesion strength. This sequential parameter adjustment enables simultaneous achievement of fine surface finish and high adhesion.
Solution Approach 2:
The patent applies periodic action through the two-stage electrolytic process where each stage has distinct operational parameters. The first electrolytic process and second electrolytic process are performed sequentially with different copper ion concentrations, creating a periodic variation in deposition conditions that first forms fine nodules and then strengthens adhesion, thereby resolving the contradiction between fineness and adhesion.
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 method effectively produces a roughening layer with low surface roughness and high peel resistance, enhancing the adhesion between the copper foil and insulating resin, which is essential for fine-line printed circuit boards.
Implementation Method 1
An electrolytic process is performed to form a roughening layer on the copper foil. An electrolyte solution in the electrolytic process includes copper ions, sulfate ions, and a coordination compound.
Implementation Method 2
An electrolytic process is performed to form a roughening layer on the copper foil. The electrolytic process uses direct current.
Implementation Method 3
a coordination compound in a range from 0.1 g/L to 10 g/L. The coordination compound includes a benzotriazole-based compound, a propanesulfonic acid-based compound, ethylenediaminetetraacetic acid or a combination thereof.
Data Source
AI summary
A manufacturing method of a roughened copper foil includes the following steps. A copper foil is provided. An electrolytic process is performed to form a roughening layer on the copper foil. An electrolyte solution in the electrolysis process includes copper ions in a range from 0.1 g/L to 20 g/L, sulfate ions in a range from 30 g/L to 120 g/L, and a coordination compound in a range from 0.1 g/L to 10 g/L.