High-Purity Copper Sulfonate via Oxidative Dissolution
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Solution Overview
Problem
Current methods for producing high-purity aqueous copper sulfonate solutions, such as using copper carbonate or electrodissolution with anion-exchange membranes, result in unsatisfactory purity and high initial costs due to impurities like sodium and chloride, and difficulties in maintaining high pH and electrolyte concentration.
Innovation Solution
The oxidative dissolution of copper metal in a sulfonic acid solution at temperatures between 60°C and 100°C, using a sulfonic acid with the general formula R—(SO3H)n, where R is a lower alkyl, alkylidene, or hydroxyalkyl group, and n is 1 or 2, to achieve a copper concentration of at least 90 g/L with minimal metal and chlorine impurities, and a pH of 2 or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper carbonate is used as the copper source in the reaction with methanesulfonic acid, then the reaction can proceed, but metal impurities such as sodium are introduced into the solution resulting in unsatisfactory purity
Solution Approach 1:
The patent extracts and eliminates the problematic copper carbonate intermediate step by directly using copper metal as the starting material. This removes the source of sodium and other metal impurities that are inherent in copper carbonate synthesis, thereby achieving high-purity copper sulfonate solution without compromising reaction feasibility
Solution Approach 2:
The patent uses copper metal directly as a disposable starting material that can be completely consumed in the oxidation reaction. This eliminates the need for purification steps to remove impurities from copper carbonate, as the copper metal itself serves as both the reactant and the pure copper source
2Reliability
If an anion-exchange membrane is used in electrodissolution to prevent copper deposition, then copper dissolution can be achieved, but chloride ions from the membrane contaminate the solution
Solution Approach 1:
The patent extracts and removes the anion-exchange membrane component from the system entirely. By using direct oxidative dissolution of copper metal in methanesulfonic acid without any membrane separation, the method eliminates chloride ion contamination while maintaining effective copper dissolution through chemical oxidation rather than electrochemical methods
Solution Approach 2:
The patent replaces the electrochemical dissolution mechanism (which requires membranes and electricity) with a direct chemical oxidation mechanism. This substitution eliminates the need for anion-exchange membranes and their associated chloride ion contamination, achieving copper dissolution through chemical reaction with oxygen in the acidic medium
3Object-affected harmful factors
If the pH of the aqueous copper sulfonate solution is increased to 2 or more, then substrate effects are reduced, but the electrolyte concentration becomes extremely low causing high solution resistance
Solution Approach 1:
The patent changes the chemical composition parameters by using methanesulfonic acid as the electrolyte medium and directly dissolving copper metal in it. This creates a solution that maintains high copper concentration and appropriate conductivity while achieving pH of 2 or more, as the sulfonate buffer system allows pH control without compromising electrolyte strength
4Ease of manufacture
If copper sulfate is used as the copper source, then the solution can be prepared, but the solubility concentration is limited to approximately 80 g/L
Solution Approach 1:
The patent changes the copper source from copper sulfate to copper metal with methanesulfonic acid as the medium. This parameter change enables much higher copper concentrations to be achieved, as the copper metal can be completely dissolved and converted to copper sulfonate without the solubility limitations of copper sulfate
Solution Approach 2:
The patent creates a composite electrolyte system combining methanesulfonic acid with copper sulfonate. This composite material system allows for higher copper concentrations than traditional sulfate-based systems, as the sulfonate complex has different solubility and stability characteristics that enable supersaturation levels
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
This method produces a high-purity aqueous copper sulfonate solution suitable for high-current-density copper electroplating in semiconductor applications, ensuring low impurity content and effective plating film formation with reduced substrate effects.
Implementation Method 1
The oxidative dissolution of copper metal in a sulfonic acid solution at temperatures between 60°C and 100°C
Implementation Method 2
The oxidative dissolution of copper metal in a sulfonic acid solution
Data Source
AI summary
An object of the present invention is to provide a high-purity aqueous copper sulfonate solution and a simplified method of producing this solution.The aqueous copper sulfonate solution of the present invention is characterized in that the copper concentration therein is at least 90 g/L, the content of metal impurities is less than 10 mg/L as metal for each metal impurity, the content of chlorine is less than 10 mg/L, and the sulfonic acid is a sulfonic acid represented by the following general formulaR—(SO3H)n (in the formula, R represents a lower alkyl group, lower alkylidene group, lower alkylene group, or hydroxyalkyl group and n represents 1 or 2).