Copper Electrolytic Solution for Low-Profile Foil
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Solution Overview
Problem
Conventional electrolytic copper foils have severe surface roughness issues, leading to difficulties in fine patterning and poor high-temperature performance, as additives like thiourea compromise elongation and tensile strength.
Innovation Solution
A copper electrolytic solution containing specific quaternary amine salts and organic sulfur compounds is used, allowing for a low-profile, finely patternable copper foil with excellent elongation and tensile strength at both ordinary and high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If additives like thiourea are used to reduce surface roughness, then the profile height is lowered, but elongation and tensile strength sharply decrease
Solution Approach 1:
The invention changes the chemical parameters of the electrolytic solution by introducing a specific organic sulfur compound with controlled molecular weight (100-1000) and sulfur content (1-20% by weight). This parameter change allows achieving low profile height while avoiding the strength deterioration caused by conventional additives like thiourea.
Solution Approach 2:
The invention uses a composite approach by combining the organic sulfur compound with specific copper salt concentrations (30-100 g/L) and controlled impurity levels (Cl: 10-200 ppm, Fe: 1-50 ppm). This composite electrolyte system achieves both low surface roughness and maintained mechanical strength.
2Productivity
If conventional electrolysis is used, then copper foil can be produced continuously, but severe bumps and pits on the rough side make fine patterning difficult
Solution Approach 1:
The invention modifies the electrolysis parameters by controlling the organic sulfur compound concentration (0.1-10 ppm), copper salt concentration (30-100 g/L), and impurity levels. These parameter changes produce a low-profile surface that enables fine patterning while maintaining continuous production capability.
3Shape
If the rough side is smoothed to achieve low profile, then fine patterning becomes possible, but conventional additives compromise high-temperature performance
Solution Approach 1:
The invention changes the molecular weight parameter of the organic sulfur compound to be within 100-1000, with sulfur content of 1-20% by weight. This specific parameter range achieves low profile height while maintaining high-temperature reliability, unlike conventional additives.
Solution Approach 2:
The invention uses trace amounts (0.1-10 ppm) of the organic sulfur compound, making it a short-living additive that works effectively in small concentrations without compromising long-term foil performance at high temperatures.
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 achieves a significant reduction in surface roughness, enabling fine patterning and maintaining high elongation and tensile strength across temperature ranges, outperforming previous methods that used single additives or no additives.
Implementation Method 1
a copper electrolytic solution is allowed to flow between the cathode drum and the anode, a potential differential is provided between these to electrodeposit copper onto the cathode drum
Implementation Method 2
electrodeposit copper onto the cathode drum
Data Source
AI summary
The present invention provides a copper electrolytic solution used to obtain a low-profile electrolytic copper foil with a low surface roughness on the rough side (the opposite side from the glossy side) in the production of an electrolytic copper foil using a cathode drum and, more particularly, to provide a copper electrolytic solution used to obtain an electrolytic copper foil that has excellent transmission loss characteristics at a high frequency, can be finely patterned, and has excellent elongation and tensile strength, both at ordinary and high temperatures. The copper electrolytic solution of the present invention contains (A) at least one quaternary amine salt selected from the group consisting of (a) quaternary amine salts obtained by a reaction between epichlorohydrin and an amine compound mixture composed of a secondary amine compound and a tertiary amine compound, and (b) polyepichlorohydrin quaternary amine salts, and (B) an organic sulfur compound.