Ninhydrin Stabilized Copper Electroplating Bath

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Solution Overview

Problem

Copper electroplating solutions containing sulfur atoms become unstable over time, leading to poor via filling ability and plating appearance issues, particularly due to the formation of decomposition products that affect deposition rates and adhesion of the copper layer.

Innovation Solution

Incorporating ninhydrin into the copper electroplating solution to reduce the concentration of decomposition products with the structure —X—S—, thereby maintaining a stable plating process and improving via filling ability without using formaldehyde.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If copper electroplating baths containing specific compounds with sulfur atoms are used to promote deposition rates near the bottom surface, then via filling ability is improved, but the bath becomes unstable over time causing lumps to form and plating appearance deteriorates

Engineering Contradiction:

Improvevia filling abilityVSAvoidbath stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent introduces a mediator substance that reacts with the harmful decomposition products (—X—S— compounds) to convert them into beneficial or harmless substances. This mediator acts as an intermediary between the sulfur-containing compounds and the plating process, transforming the harmful effect into a useful one by maintaining bath stability while preserving via-filling capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful decomposition products (—X—S— compounds) into beneficial substances through chemical reaction. By adding a substance that reacts with these decomposition products to form useful compounds, the invention transforms the harmful instability and lump formation into a beneficial effect that maintains plating quality and bath stability over time.

Inventive Principle:

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

2Manufacturing precision

If conventional sulfur-containing compounds are used in copper electroplating, then initial via filling is good, but throwing power decreases and reliability with respect to thermal shocks decreases over time

Engineering Contradiction:

Improvevia filling abilityVSAvoidthermal shock reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent converts the harmful decomposition products into beneficial substances that actually enhance throwing power and thermal shock reliability. By reacting the —X—S— decomposition products with the added substance to form useful compounds, the invention transforms what would be harmful accumulation into a beneficial effect that improves long-term plating reliability and resistance to thermal shocks.

Inventive Principle:

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

Solution Approach 2:

The patent implements a feedback mechanism where the reaction between the added substance and decomposition products continuously regulates the chemical composition of the bath. This feedback loop prevents the accumulation of harmful substances and maintains optimal conditions for throwing power and thermal shock reliability throughout the plating process.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If formaldehyde is used to improve via filling ability, then filling performance is enhanced, but environmental and safety concerns arise due to low flash point and health effects

Engineering Contradiction:

Improvevia filling abilityVSAvoidenvironmental and safety hazards

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces formaldehyde with a safer, environmentally friendly substance that can be easily added to the plating bath. This substitute substance performs the same function of improving via filling ability without the harmful properties of formaldehyde, effectively replacing a dangerous chemical with a benign alternative that achieves the same technical result.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 use of ninhydrin in the copper electroplating solution stabilizes the plating process, enhances via filling ability, and maintains a glossy appearance by controlling the concentration of —X—S— decomposition products, ensuring complete filling of vias without gaps.

Implementation Method 1

Incorporating ninhydrin into the copper electroplating solution to reduce the concentration of decomposition products with the structure —X—S—

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

copper electroplating solution and method of copper electroplating

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Data Source

PatentUS9175413B2Copper electroplating solution and method of copper electroplating

Publication Date: 2015.11.03 DUPONT ELECTRONIC MATERIALS INT LLC

AI summary

A copper electroplating solution which contains compounds with the structure —X—S—Y— wherein X and Y are, independently atoms selected from a group consisting of hydrogen, carbon, sulfur, nitrogen, and oxygen, and X and Y can be the same only if they are carbon atoms and ninhydrin. By using this copper electroplating solution, it is possible to form good filled vias without worsening the appearance of the plating.