Tin Electrorefining Additive Synergy for Dendrite Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Tin electrorefining using sulphuric acid suffers from dendritic growth issues, leading to decreased efficiency and purity, particularly in achieving the high purity required for electronic applications, and existing additives face solubility challenges and contamination problems.
Innovation Solution
A combination of gelatine and a compound of general formula (I), such as bisphenol sulfone or di-tolyl sulfoxide, is used in a sulphuric acid bath to enhance tin electrorefining, providing a synergistic effect that prevents dendritic growth and achieves high purity tin deposits with improved morphology and reduced porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If gelatine is used as additive in an electrolytic sulphuric acid bath, then the tin deposit morphology is improved, but the electrorefined tin metal becomes porous and undergoes violent oxidation, decreasing the final yield
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a specific compound of formula (I) with defined molecular structure and properties. This compound modifies the electrolyte composition to control the deposition process, reducing porosity and oxidation while maintaining smooth morphology through parameter optimization.
Solution Approach 2:
The patent creates a composite additive system combining gelatine with the compound of formula (I). This composite approach leverages the morphological control of gelatine while the compound of formula (I) provides oxidation resistance and reduces porosity, achieving synergistic effects that resolve the contradiction between morphology improvement and oxidation resistance.
2Shape
If bisphenol sulfone is used alone as additive, then dendritic growth is reduced, but vigorous agitation is required and suspended additive particles get trapped at the cathode, contaminating the tin electrodeposition
Solution Approach 1:
The patent modifies the additive concentration parameters and introduces the compound of formula (I) which has different solubility and interaction properties. This changes the operational parameters, reducing the need for vigorous agitation and preventing particle suspension, thereby resolving the ease of operation and manufacturing precision issues.
Solution Approach 2:
The compound of formula (I) acts as an intermediary substance that mediates between the gelatine and the tin ions in the electrolyte. It facilitates smooth deposition without requiring vigorous agitation and prevents contamination by acting as a protective intermediary layer during the electrodeposition process.
3Ease of manufacture
If sulphuric acid is used as electrolyte, then environmental friendliness and cost are improved, but dendritic growth occurs on the anode, decreasing tin electrodeposition efficiency
Solution Approach 1:
The patent introduces organic additives (gelatine and compound of formula (I)) to modify the electrolyte parameters. These additives change the deposition kinetics and surface properties, preventing dendritic growth while maintaining the benefits of sulphuric acid as the base electrolyte, thus resolving the contradiction between cost-effectiveness and productivity.
Solution Approach 2:
The patent applies local quality modification by introducing additives that specifically affect the electrode surface properties where deposition occurs. The gelatine and compound of formula (I) create a localized modified environment at the electrode interface that prevents dendritic growth, while the bulk electrolyte maintains the cost-effective sulphuric acid composition.
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 combination of gelatine and the specified compound in the sulphuric acid bath results in high-purity tin deposits (≥ 99.9%) with reduced porosity and oxidation, effectively addressing the challenges of dendritic growth and contamination, meeting the purity requirements for electronic applications.
Implementation Method 1
At the negative charged cathode, the tin cations are reduced and deposit as neutral tin atoms
Implementation Method 2
tin electrodeposition using sulphuric acid suffer from deposition of tin species in the shape of needles, whiskers and dendrites on the surface of the anode, which is commonly known as 'dendritic growth'
Implementation Method 3
an ionically conducting liquid (aqueous electrolyte) containing tin metal dissolved as positive ions
Implementation Method 4
At the negative charged cathode, the tin cations are reduced and deposit as neutral tin atoms
Implementation Method 5
the electrorefined tin metal is mostly porous, which results in a violent oxidation with atmospheric air
Data Source
Figure 1a~2c
Figure 3~4d
AI summary
The present invention relates to an electrolytic sulphuric acid bath comprising a mixture of gelatine and a compound of general formula (I) as additives, to a method for electrorefining of tin comprising applying a current to the electrolytic sulphuric acid bath of the present invention, and to the synergistic use of gelatine and a compound of general formula (I) as additives in an electrolytic sulphuric acid bath for tin electrorefining.