Electrolyte Bath Regeneration via Anion Exchange
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Solution Overview
Problem
Metallization baths used in metal deposition without an outside current face limitations in durability and applicability due to pH changes and anion enrichment, particularly in alkaline environments, where existing methods like electrodialysis are not applicable for copper or other metals.
Innovation Solution
A method involving the regeneration of electrolyte baths through partial flow extraction, dialysis or electrodialysis using anion-selective membranes to exchange anions like sulfate or formate ions for hydroxide ions, with counter-solutions of alkali or alkaline earth hydroxides, and replenishing metal sources and reducing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional maintenance methods (adding alkali hydroxides and replenishing copper sulfate and formaldehyde) are used, then the electrolyte can be maintained in a workable pH range, but the chemical and physical characteristics of the electrolyte change leading to limited durability and applicability
Solution Approach 1:
The patent extracts and removes anions (sulfate, formate, phosphate) that accumulate during the metallization process through dialysis and electrodialysis processes. This extraction prevents the harmful buildup of these anions that would otherwise change the electrolyte's chemical characteristics and limit its durability, while maintaining the essential metal ions and pH balance.
Solution Approach 2:
The patent discards harmful anions through selective removal via dialysis membranes and electrodialysis, while recovering and retaining the beneficial components (metal ions, complexing agents). This selective discarding and recovering maintains the electrolyte's effective composition for extended periods, improving both durability and compositional stability.
2Duration of action of stationary object
If dialysis and/or electrodialysis with anion-selective membranes is used for regeneration, then anions are exchanged via ion-selective membrane, but the device complexity increases
Solution Approach 1:
The patent introduces dialysis membranes and electrodialysis cells as intermediary devices that facilitate the selective removal of anions. These intermediaries enable the regeneration process by acting as selective barriers that allow harmful anions to be removed while retaining beneficial electrolyte components, thus extending operational life despite the added device complexity.
Solution Approach 2:
The patent changes the operational parameters of the electrolyte system by implementing continuous or periodic dialysis and electrodialysis processes. This parameter change (from simple replenishment to active regeneration) extends the electrolyte's operational life by maintaining optimal composition, justifying the increased device complexity through improved performance and reduced waste.
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 extends the operational life and usability of metallization baths by maintaining stable pH and electrolyte composition, suitable for copper, nickel, and gold deposition without a current, enhancing bath durability and applicability.
Implementation Method 1
the anions released during the metallization process without a current are exchanged via an ion-selective membrane
Implementation Method 2
supplied to a dialysis and/or electrodialysis unit, in which the anions released during the metallization process without a current are exchanged
Implementation Method 3
supplied to a dialysis and/or electrodialysis unit, in which the anions released during the metallization process without a current are exchanged
Implementation Method 4
Formaldehyde or a comparable reducing agent, which, as the result of an oxidation reaction to the formate or to the corresponding anion, provides the electrons needed for the reduction of the copper
Data Source
AI summary
A method for the regeneration of an electrolyte bath used for an electroless metallization process. A partial flow of electrolyte is removed from the process vessel and regenerated by dialysis or electrodialysis. Metallization components are replenished. The partial flow is returned to the process vessel.