Sn-Alloy Electroplating Using Anion-Exchange Membrane
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Solution Overview
Problem
During electroplating with Sn-alloy, metal deposition on the anode occurs even when the process is not energized, leading to inefficiencies and the need for anode removal, and existing methods using cation-exchange membranes do not fully prevent substitution deposition on soluble anodes.
Innovation Solution
The use of an anion-exchange membrane to divide the plating tank into a cathode cell and an anode cell, where the plating solution with Sn ions is supplied to the cathode cell and an acid solution to the anode cell, allowing Sn ions to be replenished from the anode, maintaining a balanced free acid concentration and preventing metal ion migration, thus preventing anode deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a soluble anode such as Sn is used for electroplating with Sn-alloy, then Sn ions can be supplied to the plating solution, but metal substitution-deposition occurs on the anode surface when the process is not energized
Solution Approach 1:
The plating tank is divided into two separate cells: a cathode cell containing the plating solution and object to be plated, and an anode cell containing the soluble Sn anode. The cells are separated by an anion-exchange membrane, allowing independent control of each cell's chemistry while maintaining ionic connectivity for plating operation.
Solution Approach 2:
An anion-exchange membrane is introduced as an intermediary between the cathode cell and anode cell. This membrane selectively allows anion transport while blocking cation migration, preventing metal substitution-deposition on the anode during non-energized periods while maintaining necessary ionic conductivity during plating operation.
2Quantity of substance
If a cation-exchange membrane is used to isolate the anode, then Sn ions can be moved to the plating tank, but the membrane does not prevent substitution-deposition on the anode in non-energized state
Solution Approach 1:
Instead of using a cation-exchange membrane that allows cation movement, the invention uses an anion-exchange membrane that allows anion movement while blocking cations. This inverted approach achieves the same goal of preventing substitution-deposition on the anode while maintaining necessary ionic connectivity for plating operation.
3Object-generated harmful factors
If an insoluble anode such as Pt is used to prevent substitution-deposition, then metal deposition on anode is avoided, but hydrogen is generated on the anode surface deteriorating electrolysis
Solution Approach 1:
The anion-exchange membrane acts as an intermediary that enables the use of soluble Sn anodes without the harmful effects. By blocking cation migration while allowing anion transport, the membrane prevents substitution-deposition on the anode during idle periods while maintaining electrolysis efficiency during active plating operation.
Solution Approach 2:
The invention changes the chemical parameters in the anode cell by adding acid solution, creating a distinct chemical environment from the cathode cell. This parameter change prevents substitution-deposition reactions on the anode surface while maintaining conditions favorable for efficient electrolysis during plating operation.
4Object-generated harmful factors
If the plating tank is divided into separate cells with an anion-exchange membrane, then substitution-deposition on anode is prevented, but the device complexity increases
Solution Approach 1:
The plating tank is segmented into two cells separated by an anion-exchange membrane. This segmentation prevents substitution-deposition on the anode while maintaining a relatively simple overall structure that can be implemented using standard electroplating tank configurations with minimal additional complexity.
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 prevents metal deposition on the anode, generates a replenishing solution for Sn ions, reduces the need for separate replenishing solutions, and lowers costs by maintaining a balanced free acid concentration, ensuring efficient electroplating without anode deposition.
Implementation Method 1
dividing an inside of a plating tank into a cathode cell and an anode cell by an anion-exchange membrane
Implementation Method 2
the free acid can be moved but Sn ions cannot pass through
Implementation Method 3
electroplating by energizing an object to be plated in the cathode cell and an anode made of Sn in the anode cell
Implementation Method 4
in the cathode cell, Sn-alloy is deposited on the object to be plated by electrolyzing
Implementation Method 5
in the anode cell, Sn ions are supplied into solution from the anode
Data Source
AI summary
To provide a method of electroplating with Sn-alloy in which a problem of deposition of metals on an anode when electroplating with Sn-alloy such as Sn—Ag based-alloy or the like is performed is solved and a soluble anode is enabled to be used. Dividing an inside of a plating tank into a cathode cell and an anode cell by an anion-exchange membrane; supplying plating solution including Sn ions to the cathode cell; supplying acid solution to the anode cell; electroplating by energizing an object to be plated in the cathode cell and an anode made of Sn in the anode cell; and using the acid solution including Sn ions liquated out form the anode made of Sn along with progress of plating as replenishing solution of Sn ions for plating solution in the cathode cell.