Stabilizing Platinum Deposition Rate via Nitrite Salt Addition

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Solution Overview

Problem

The existing methods for electroplating platinum face challenges in depositing thick layers due to high internal stresses, cracking, and instability of electrolytes over long electrolysis durations, leading to reduced deposition rates and increased hydrogen co-deposition.

Innovation Solution

A method is introduced to stabilize platinum deposition by adding a soluble nitrite salt, such as sodium nitrite, to an acidic, aqueous cyanide-free electrolyte bath containing a platinum sulfamate complex, which destroys the amidosulfonic acid released during electrolysis, thereby extending the electrolyte's useful life and maintaining deposition rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If platinum is deposited from a sulfamate complex electrolyte, then initial deposition rate is acceptable, but deposition rate continuously falls over time

Engineering Contradiction:

Improvedeposition rateVSAvoidelectrolyte useful life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent converts the harmful effect of amidosulfonic acid accumulation (which causes deposition rate decline) into a beneficial process by intentionally adding nitrite salts that react with and destroy the amidosulfonic acid. The harmful substance released during electrolysis is transformed from a problem into a controlled reaction intermediate that is immediately eliminated, thereby maintaining stable deposition rates throughout extended electrolysis periods.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The nitrite salt acts as an intermediary substance that mediates between the platinum sulfamate complex and the amidosulfonic acid byproduct. It provides a chemical pathway to destroy the harmful amidosulfonic acid through reaction (NH2SO3H + NaNO2 → N2 + H2O + NaHSO4), preventing its accumulation and the associated decline in deposition rate, thus extending electrolyte useful life.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Length of moving object

If electrolysis duration is extended for thick layer deposition, then layer thickness increases, but electrolyte stability decreases and decomposition occurs

Engineering Contradiction:

Improvelayer thicknessVSAvoidelectrolyte stability

Core Design Contradiction:

Length of moving objectVSStability of the object's composition

Solution Approach 1:

The patent addresses electrolyte decomposition during extended electrolysis by converting the harmful amidosulfonic acid byproduct into beneficial nitrogen gas and water through reaction with nitrite salts. This eliminates the root cause of electrolyte instability, allowing prolonged electrolysis durations necessary for thick layer deposition without the electrolyte decomposing.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Length of moving object

If electrolysis duration is extended, then thick layers can be deposited, but internal stresses increase causing cracking

Engineering Contradiction:

Improvelayer thicknessVSAvoidlayer integrity

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The patent prevents cracking in thick platinum layers by converting the harmful amidosulfonic acid into nitrogen gas and water through nitrite salt reaction. This eliminates the chemical cause of internal stress accumulation, allowing extended electrolysis for thick layer deposition while maintaining layer integrity and preventing crack formation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Productivity

If electrolysis continues for extended periods, then more platinum can be deposited, but hydrogen co-deposition increases

Engineering Contradiction:

Improvetotal platinum depositedVSAvoidhydrogen co-deposition

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent reduces hydrogen co-deposition during extended electrolysis by converting the harmful amidosulfonic acid into nitrogen gas and water through nitrite salt reaction. This chemical transformation removes the source of hydrogen evolution, allowing continued high-productivity deposition without increasing hydrogen contamination in the platinum layer.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 significantly extends the useful life of the electrolyte, reduces operating costs, and maintains the quality and thickness of platinum layers by preventing amidosulfonic acid accumulation, ensuring stable and economic platinum deposition.

Implementation Method 1

a quantity of a soluble nitrite salt corresponding to the amidosulfonic acid is added to the bath in order to destroy said amidosulfonic acid

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

method for stabilizing the deposition of platinum from an acidic, aqueous, cyanide-free electrolyte bath containing a platinum sulfamate complex

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Data Source

PatentUS20240060203A1Stabilization of the Deposition Rate of Platinum Electrolytes

Publication Date: 2024.02.22 UMICORE GALVANOTECHNIK GMBH

AI summary

The present invention is directed toward a method for stabilizing the electrolytic deposition of platinum from an electrolytic bath. In particular, the present invention relates to a corresponding method in which the platinum electrolytic bath has platinum in the form of a sulfamate complex.