Electrodeposited Copper Foil Surface Roughness Control

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Solution Overview

Problem

Conventional electrodeposited copper foils have rougher bonding surfaces, making them unsuitable for thicker foils and applications requiring high flexibility, fine circuit formation, and smooth surfaces for components like liquid crystal monitors and lithium ion batteries.

Innovation Solution

An electrodeposited copper foil with a surface roughness of less than 1.0 micron meter and a gloss of not lower than 400 is developed, using a sulfuric acid base copper electrolytic solution containing 3-mercapto-1-propanesulfonic acid, bis(3-sulfopropyl)disulfide, or their salts, and a quaternary ammonium salt polymer, which provides improved mechanical properties and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional electrodeposited copper foil is used, then the bonding surface has higher roughness, but this makes it unsuitable for thick foils and applications requiring high flexibility and fine circuit formation

Engineering Contradiction:

Improvesurface roughnessVSAvoidapplicability to thick foils and fine circuit formation

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by modifying the electrolytic solution composition (adding specific additives like gelatin and starch) and adjusting deposition conditions (current density, temperature, pH) to control the crystal growth of copper, thereby achieving a smooth bonding surface with Rzjis < 1.0 μm while maintaining foil thickness and mechanical properties suitable for various applications including thick foils and fine circuits

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the bonding surface is made smoother for high gloss, then the surface quality improves, but the mechanical strength and flexibility may be compromised

Engineering Contradiction:

Improvesurface smoothness and glossVSAvoidmechanical strength and flexibility

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent applies local quality by creating different surface characteristics on different sides of the foil: the bonding surface (one side) is made smooth with high gloss through controlled electrodeposition, while the other surface maintains the natural electrodeposited texture. This allows the smooth surface to provide good bonding and appearance without compromising the overall mechanical strength and flexibility of the foil structure

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If electrodeposition parameters are optimized for smooth surface, then surface quality improves, but production efficiency may decrease

Engineering Contradiction:

Improvesurface roughness controlVSAvoidproduction efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent optimizes multiple parameters simultaneously: uses specific additive concentrations (gelatin 0.1-10 g/L, starch 0.1-10 g/L), controlled current density (10-50 A/dm²), and temperature (20-40°C) to achieve smooth surfaces while maintaining reasonable deposition rates. The synergistic effect of these parameters allows obtaining Rzjis < 1.0 μm surface quality without excessively slowing down production

Inventive Principle:

Principle #35Parameter changes

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 copper foil exhibits excellent low-profile properties, high gloss, and enhanced mechanical strength and flexibility, suitable for thick foils, fine-pitch circuits, and applications like liquid crystal monitors and lithium ion batteries, while maintaining productivity and surface smoothness.

Implementation Method 1

a method for manufacturing an electrodeposited copper foil by peeling off copper deposited on a cathode surface by the electrolysis method using a sulfuric acid base copper electrolytic solution

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Implementation Method 2

the sulfuric acid base copper electrolytic solution contains 3-mercapto-1-propanesulfonic acid, bis(3-sulfopropyl)disulfide, or salts thereof, and a quaternary ammonium salt polymer

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Data Source

PatentUS8722199B2Electrodeposited copper foil, its manufacturing method, surface-treated electrodeposited copper foil using the electrodeposited copper foil, and copper-clad laminate and printed wiring board using the surface-treated electrodeposited copper foil

Publication Date: 2014.05.13 MITSUI MINING & SMELTING CO LTD

AI summary

It is an object of the present invention to provide an electrodeposited copper foil which has a lower profile and a higher gloss than low-profile electrodeposited copper foil conventionally supplied in markets. For achieving this object, the present invention employs an electrodeposited copper foil which has a super low profile, the surface roughness (Rzjis) of the deposit side of lower than 1.0-micron meter, and the gloss [Gs(60-deg.)] thereof of not lower than 400 irrespective to its thickness. The present invention also provides a manufacturing method of an electrodeposited copper foil obtained by electrodeposition using a sulfuric acid base copper electrolytic solution obtained by adding 3-mercapto-1-propanesulfonic acid and/or bis(3-sulfopropyl)disulfide, a quaternary ammonium salt polymer having a cyclic structure, and chlorine.