High Purity Copper Sulfate Production via Thermal Concentration
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Solution Overview
Problem
Existing methods for purifying copper sulfate to high purity levels, such as 4N to 5N, are inefficient and costly, particularly when trying to remove impurities like Ni, Fe, Cr, Ag, Cl, alkali metals, and Si oxides, which are detrimental in electroplating processes for semiconductor devices.
Innovation Solution
A method involving dissolving commercially available copper sulfate crystals in purified water, followed by thermal concentration, filtration, and desiccation, which reduces impurities to 1 wtppm or less, achieving high purity copper sulfate with a purity of 99.99 wt % or higher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrolytic copper powder with acid treatment is used to remove Ni, then Ni content is reduced, but the process becomes complex and costly
Solution Approach 1:
The patent changes the purification parameters by using thermal concentration at specific temperatures (80-100°C) and controlling evaporation to precipitate impurities. This replaces the complex acid treatment process with a simpler thermal process that achieves the same purity improvement (from 95-99.9% to 99.99% or higher) without requiring multiple treatment steps
Solution Approach 2:
The patent extracts impurities from the copper sulfate solution by controlling thermal evaporation to precipitate them as solid crystals that can be easily filtered out. This separates the impurity removal function from the complex acid treatment process, achieving purification through simple filtration after thermal concentration
2Manufacturing precision
If multiple purification steps are applied to achieve 4N to 5N purity, then impurity content is reduced, but production time and cost increase
Solution Approach 1:
The patent merges dissolution, thermal concentration, and purification into a single integrated process. By dissolving copper sulfate crystals in purified water and applying controlled thermal evaporation, multiple purification functions are combined into one continuous operation, achieving 99.99% purity without requiring separate treatment steps for each impurity type
Solution Approach 2:
The patent utilizes phase transition during thermal concentration, where impurities precipitate from the solution as solid crystals when the solution is evaporated to specific concentrations. This natural phase change enables automatic separation of impurities from the copper sulfate solution, achieving high purification efficiency in a single step
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 effectively and economically removes impurities, resulting in high purity copper sulfate suitable for semiconductor applications, with significant improvements in electroplating performance by minimizing foreign matter and enhancing embedding characteristics.
Implementation Method 1
dissolving copper sulfate crystals in purified water
Implementation Method 2
performing evaporative concentration thereto
Implementation Method 3
subjecting this to filtration to obtain high purity copper sulfate
Implementation Method 4
performing further evaporative concentration to effect crystallization
Implementation Method 5
performing desiccation thereto; the desiccation temperature is 40 to 100° C.
Data Source
AI summary
High purity copper sulfate having a purity of 99.99% or higher and in which the content of transition metals such as Fe, Cr, Ni is 3 wtppm or less; and a method for producing such high purity copper sulfate which includes the steps of dissolving copper sulfate crystals in purified water, performing evaporative concentration thereto, removing the crystals precipitated initially, performing further evaporative concentration to effect crystallization, and subjecting this to filtration to obtain high purity copper sulfate. This manufacturing method of high purity copper sulfate allows the efficient removal of impurities from commercially available copper sulfate crystals at a low cost through dissolution with purified water and thermal concentration.