Surface Treated Copper Foil Etching Factor Optimization
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Solution Overview
Problem
Ordinary surface treated copper foils have an etching rate imbalance between the surface treatment layer and the copper foil, leading to a tapered etching shape and increased space between circuit patterns, making it difficult to achieve a reduced pitch in circuit patterns, thus limiting circuit formability.
Innovation Solution
The surface treatment layer on the copper foil is optimized by controlling the Ni concentration within a specific range (0.1 to 15.0 atm %) and Zn concentration (5.0 to 40.0 atm %) to enhance etching factor and heat resistance, allowing for improved circuit formability and reduced pitch in printed circuit boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surface treatment layer is formed on copper foil to improve adhesion and surface properties, then surface treatment effectiveness is improved, but the etching rate of the surface treatment layer becomes slower than the copper foil, causing tapered etching shape and reduced etching factor
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Ni concentration within 0.1 to 15.0 atm% and Zn concentration within 5.0 to 40.0 atm% in the surface treatment layer. This optimization balances the etching rate between the surface treatment layer and copper foil, preventing excessive tapering while maintaining surface treatment effectiveness. The controlled composition ensures the surface layer etches at a comparable rate to the underlying copper, improving etching factor without sacrificing adhesion or surface properties.
Solution Approach 2:
The patent employs composite materials by creating a multi-element surface treatment layer containing Ni, Zn, and other elements (Cr, Co, Si, Cu) in specific proportions. This composite structure combines the benefits of different elements: Ni provides adhesion and controlled etching, Zn enhances surface properties and etching resistance, while other elements contribute to overall performance. The composite nature allows simultaneous optimization of adhesion, etching characteristics, and surface treatment effectiveness.
2Duration of action of stationary object
If the etching rate of surface treatment layer is slower than copper foil, then surface treatment durability is improved, but the circuit pattern space must be increased, making reduction in pitch difficult
Solution Approach 1:
The patent utilizes parameter changes by optimizing the Ni concentration (0.1 to 15.0 atm%) and Zn concentration (5.0 to 40.0 atm%) to achieve a balanced etching rate. This balance allows the surface treatment layer to maintain durability while etching at a rate comparable to the copper foil, thereby maintaining a high etching factor. Consequently, circuit patterns can be closely spaced without requiring excessive clearance, enabling pitch reduction while preserving surface treatment durability.
3Strength
If Ni concentration in surface treatment layer is increased to improve adhesion, then adhesion strength is improved, but etching rate decreases further, worsening etching factor
Solution Approach 1:
The patent applies parameter changes by precisely controlling Ni concentration within 0.1 to 15.0 atm%, avoiding excessive Ni content that would cause slow etching. Simultaneously, Zn concentration is optimized within 5.0 to 40.0 atm% to compensate and maintain adhesion strength. This balanced composition ensures adequate adhesion while preventing excessive etching resistance, thereby maintaining a high etching factor for precise circuit pattern formation.
Solution Approach 2:
The patent employs composite materials by combining Ni with Zn and other elements in specific proportions. The Ni component provides adhesion strength, while the Zn component contributes to surface properties and modulates etching behavior. This composite approach allows the surface treatment layer to achieve both strong adhesion and appropriate etching characteristics, resolving the contradiction between adhesion strength and etching factor.
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 optimized surface treatment layer significantly enhances circuit formability and enables the production of printed circuit boards with reduced pitch, while maintaining high heat resistance and chemical resistance, and preventing etching residue and adhesion issues.
Implementation Method 1
the surface of a copper foil is subjected to a roughening treatment through copper-cobalt-nickel alloy plating
Implementation Method 2
an XPS depth profile obtained by performing sputtering at a sputtering rate of 2.5 nm/min (in terms of SiO2) for 1 minute
Data Source
AI summary
A surface treated copper foil 1 includes a copper foil 2, and a first surface treatment layer 3 formed on one surface of the copper foil 2. The first surface treatment layer 3 of the surface treated copper foil 1 has a Ni concentration of 0.1 to 15.0 atm % based on the total amount of elements of C, N, O, Zn, Cr, Ni, Co, Si, and Cu, in an XPS depth profile obtained by performing sputtering at a sputtering rate of 2.5 nm/min (in terms of SiO2) for 1 minute. A copper clad laminate 10 includes the surface treated copper foil 1 and an insulating substrate 11 adhered to the first surface treatment layer 3 of the surface treated copper foil 1.