High purity electrolytic sulfonic acid solutions

Abstract

Disclosed is a solution for an electrochemical process, the solution containing a sulfonic acid and having a low concentration of sulfur compounds, either low or high valence, that are susceptible to reduction and which is intended for use in electrodeposition, batteries, conductive polymers and descaling processes.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to high purity sulfonic acids and their use in electrochemical processes, methods for preparing such high purity acids, methods for preparing high purity metal-sulfonate or sulfonic acid solutions, and products formed by using such methods and solutions. [0003] 2. Prior Art[0004] Electrochemical processes may contain acid electrolytes to impart conductivity and thus lower the required voltage, aid in the dissolution of metal (e.g. formation of metal salts) and metal oxides (e.g., descaling), aid in the deposition of metals from aqueous solutions (e.g., electrodeposition), and may be used in the synthesis of conductive polymers to provide proton conduction and in batteries to aid in the dissolution and salvation of metals such as zinc and lead. [0005] There are many acids that may be used in the above applications such as sulfuric, nitric, phosphoric, sulfamic, and hydrochloric acid as w...

AI Technical Summary

Benefits of technology

[0025] The compositions of the invention are useful for depositing a metal, modifying or cleaning a scaled metal surface or for use as acid electrolytes in batteries or during the synthesis of conductive polymers.

Problems solved by technology

Sulfuric acid is not often used in the electrodeposition of silver or lead-based alloys due to the likelihood of metal precipitation in this acid.

However, even with the improvements in electroplating processes, circumstances may exist that can lead to plating defects due to inadequate coverage in recess areas such as in the vias or trenches or through-holes in electronic devices, poor corrosion resistance of the deposited metal, too high a residual stress leading to cracking in the metal coating or a rough, commercially unacceptable deposit.

These defects can occur as a result of an imbalance of the organic additives intended to obtain the desired metallic coating.

However, combinations of various low-valent sulfur compounds is typically unwanted due to competitive interactions at the surface of the work piece.

If the nickel electrolytes are made using impure sulfonic acids such as those containing reduced or easily reducible sulfur compounds, the likelihood of sulfur incorporation increases significantly thus affecting the resultant stress in the deposit, the brightness of the metallic coating and the corrosion properties.

However, reducible sulfur compounds, if present in impure sulfonic acids, may alter the grain size of the nickel deposit and consequentially alter the stress in the metallic nickel deposit.

The synthesis of sulfonic acids may be complex and several undesirable impurities may be present in the desired sulfonic acids leading to difficulties in using sulfonic acids in electrochemical processes.

Many low valent sulfur compounds such as sulfur (II) or sulfur (IV) or higher valent sulfur molecules such as sulfur (VI) compounds that are susceptible to reduction and are present in the sulfonic acid may produce a stench or odor, interfere with the ongoing electrochemical process or alter the final product.

Low valent or easily reducible sulfur compounds in an acidic medium may also produce an undesired sulfur stench.

These materials are unwanted and dangerous during electrochemical processes.

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