Electrodeposited Copper Foil Surface Roughness Control
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Solution Overview
Problem
Existing copper foils used in batteries and electronic components face challenges such as high fabrication costs, contamination from lubricating oils, mechanical weakness, and difficulty in achieving low roughness and high elongation rates, which affect their performance and reliability in high-temperature applications.
Innovation Solution
An electrodeposited copper foil with specific surface roughness characteristics (1.5≤(Rmax−Rz)/Ra≤6.5) is developed, offering high tensile strength (40 kgf/mm2 to 70 kgf/mm2) and elongation rate (2% to 15%) before and after heat treatment, along with low roughness and improved glossiness, reducing the risk of corner curling and enhancing adhesion with active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rolled copper foil is used, then the fabrication cost is high and it is difficult to fabricate a copper foil having a wide width, but the mechanical strength is sufficient
Solution Approach 1:
The patent replaces the mechanical rolling process with an electrodeposition process. Instead of mechanically rolling copper to form foil, the invention uses electrochemical deposition from an electrolyte solution containing copper ions, allowing for wide-width foil production at lower cost while achieving the required mechanical properties through controlled deposition parameters and substrate treatment
Solution Approach 2:
The invention changes the fundamental manufacturing parameter from mechanical deformation (rolling) to electrochemical deposition. By controlling deposition current density, electrolyte composition, temperature, and deposition time, the process achieves both cost efficiency and mechanical strength, producing foil with controlled grain structure and surface properties that compensate for the absence of mechanical working
2Strength
If a rolled copper foil is used, then the mechanical strength is sufficient, but adhesion with an active material is degraded by contamination of the lubricating oil
Solution Approach 1:
The invention extracts and eliminates the harmful element (lubricating oil) from the manufacturing process by completely replacing the rolling process with electrodeposition. This removes the source of contamination that degrades adhesion, while still achieving sufficient mechanical strength through the electrochemical process and controlled foil structure
Solution Approach 2:
The invention uses a disposable substrate (such as a sacrificial anode or temporary support) during electrodeposition that can be easily removed or discarded, leaving a clean copper foil surface free from lubricating oil contamination. This ensures excellent adhesion properties without compromising mechanical strength
3Strength
If a thick copper foil is used, then the mechanical strength is sufficient, but the etching time is increased and lateral wall verticality of a wiring pattern is degraded
Solution Approach 1:
The invention changes the thickness parameter of the copper foil to optimized thin specifications (e.g., 6-18 μm) that are suitable for fine-pitch circuit board fabrication. This thinner foil reduces etching time and improves lateral wall verticality while the electrodeposition process and controlled grain structure maintain sufficient mechanical strength for handling and assembly
4Manufacturing precision
If a thin copper foil is used, then the etching time is reduced and lateral wall verticality is improved, but the mechanical strength is weak
Solution Approach 1:
The invention optimizes the foil thickness parameter to a thin range (6-18 μm) that enables fine-pitch etching with good verticality and reasonable etching time. Simultaneously, the electrodeposition process parameters (current density, electrolyte composition, temperature, additives) are adjusted to produce a dense, fine-grained structure that compensates for the reduced thickness and provides sufficient mechanical strength for handling and assembly
5Strength
If the tensile strength of the copper foil is high, then the resistance to wrinkle and bending is improved, but the elongation rate is decreased
Solution Approach 1:
The invention creates different local properties within the foil structure: the surface and grain boundary regions are optimized for mechanical rigidity and resistance to wrinkling and bending, while the bulk material maintains ductility and elongation capability. This is achieved through controlled grain size, orientation, and phase distribution in the electrodeposited structure
Solution Approach 2:
The invention creates a composite microstructure within the copper foil, combining different crystal phases, grain sizes, and orientations that provide both high strength (resistance to wrinkle and bending) and adequate elongation. The electrodeposition process produces a refined microstructure with dispersed phases that contribute to both mechanical properties simultaneously
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 electrodeposited copper foil exhibits high mechanical strength, high elongation rate, and low roughness, improving product reliability and reducing defects in applications like batteries and printed circuit boards, while maintaining strength and elongation properties after high-temperature heat treatment.
Implementation Method 1
an electrodeposited copper foil
Implementation Method 2
after a high-temperature heat treatment
Data Source
AI summary
Disclosed is an electrodeposited copper foil, in which a center line roughness average Ra (μm), a maximum height Rmax (μm), and a ten-point height average Rz (μm) of a matte side satisfy an Equation below, 1.5≤(Rmax−Rz)/Ra≤6.5. The electrodeposited copper foil according to the present invention maintains low roughness and high strength, and exhibits a high elongation rate, and particularly, has excellent glossiness, so that the electrodeposited copper foil may be used in a current collector of a medium and large lithigum ion secondary battery and a semiconductor packaging substrate for Tape Automated Bonding (TAB) used in a Tape Carrier Package (TCP).