Mono-ox-SPS Quantitation in Acid Copper Plating Baths

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Solution Overview

Problem

The challenge lies in accurately quantifying Mono-ox-SPS, a breakdown product of bis-(3-sulfopropyl) disulfide (SPS), in acid copper plating baths without using standard chemicals, due to issues like commercial availability and the practicality of synthesis, as well as the shifting retention time of Mono-ox-SPS peaks in HPLC analysis, making it difficult to identify and measure reliably.

Innovation Solution

A method involving spiking a predetermined amount of oxidant into the copper plating bath to generate Mono-ox-SPS, using HPLC for analysis, and calculating its concentration based on the stoichiometric relation between the oxidant and SPS, establishing a calibration curve to correlate the detector signal with the concentration increase, thereby enabling absolute value quantitation without relying on standard chemicals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If standard chemical (Mono-ox-SPS) is used for quantitation, then measurement precision is improved, but ease of manufacture deteriorates due to commercial availability issues and synthesis practicality

Engineering Contradiction:

Improvequantitation accuracyVSAvoidstandard chemical availability

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The system generates its own calibration standards by performing in-situ oxidation of SPS within the plating bath using controlled oxidant addition. This self-service approach eliminates dependence on external commercial standards while maintaining measurement accuracy through stoichiometric calculations based on known oxidant-SPS reaction ratios.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

An oxidant is introduced as an intermediary substance to convert SPS into Mono-ox-SPS in a controlled manner. This intermediary enables the generation of known quantities of the breakdown product without requiring direct access to commercial Mono-ox-SPS standards, bridging the gap between available materials and measurement needs.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If HPLC column is used for separation, then measurement precision is improved, but reliability deteriorates due to retention time shifting as column ages

Engineering Contradiction:

Improvepeak separationVSAvoidretention time stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The system continuously monitors retention time variations and uses this feedback to dynamically adjust identification criteria. By tracking shifts in retention time patterns over time, the system adapts to column aging effects while maintaining accurate peak identification through pattern recognition rather than fixed retention time thresholds.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The method performs preliminary in-situ generation of Mono-ox-SPS before HPLC analysis, creating a known quantity of the target compound with characteristic spectral and chromatographic properties. This preliminary action establishes reference patterns that can be recognized even when retention times shift, allowing reliable identification independent of column age.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If frequent monitoring is implemented, then reliability is improved, but loss of time increases due to analysis frequency

Engineering Contradiction:

Improvebreakdown product monitoringVSAvoidanalysis time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs rapid in-situ oxidation using controlled, partial addition of oxidant to generate sufficient Mono-ox-SPS for detection without requiring complete conversion. This partial action approach enables quick generation of detectable levels of the breakdown product, allowing frequent monitoring with minimal time investment per analysis.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The method replaces time-consuming manual standard preparation and extensive HPLC method development with a rapid in-situ chemical reaction approach. By substituting mechanical/chemical preparation steps with a controlled oxidation reaction that proceeds quickly in the plating bath, the system achieves frequent monitoring capability with reduced analysis time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach allows for reliable and accurate quantitation of Mono-ox-SPS across different copper plating tools, ensuring precise measurement of breakdown products, even in aged plating baths, without relying on commercial additives, and can be applied to other unstable reaction products.

Implementation Method 1

generating a breakdown product by oxidizing SPS

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

analyzing SPS values by High-Performance Liquid Chromatography (HPLC)

Methodology Applied

Scientific EffectChromatography: Chromatography

Data Source

PatentUS20240337628A1Quantitation of unstable reaction product or breakdown product without usage of standard chemical

Publication Date: 2024.10.10 ECI TECHNOLOGY INC

AI summary

The present subject matter relates to techniques for quantitation of an unstable or breakdown product generated from a raw material, e.g., bis (3-sulfopropyl)-disulfide (SPS) in acid copper plating baths. The disclosed techniques include spiking oxidant into the copper bath solution and analyzing HPLC response to quantify the absolute value of the unstable or breakdown with accuracy and precision.