Electrolytic Copper Plating Process for Confined Spaces
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Solution Overview
Problem
Existing electrolytic copper plating solutions struggle to effectively plate in confined spaces such as small vias and through-holes on printed circuit boards due to issues with wettability, mass transport, and electrical effects, failing to meet industry specifications for miniaturized electronic features.
Innovation Solution
A process involving a pre-treatment with a sulfur-containing organic compound followed by an electrolytic copper plating solution containing copper ions, alkane sulfonic acid, chloride ions, and additives like aldehydes or ketones, along with surfactants, brighteners, and leveling agents, to enhance copper deposition in confined areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrolytic copper plating solutions are used, then plating can be performed on standard surfaces, but plating in confined spaces such as small vias and through-holes fails to meet industry specifications
Solution Approach 1:
The patent modifies the chemical parameters of the plating solution by incorporating specific organic additives (suppressors and anti-suppressors) that change the electrochemical behavior of copper deposition. These parameter changes enable the solution to adapt to confined geometries by controlling nucleation and growth rates, thereby achieving uniform plating in small vias and through-holes while maintaining versatility for different substrate geometries
Solution Approach 2:
The patent employs additives that create local variations in plating characteristics. The suppressor and anti-suppressor compounds interact differently in confined versus open spaces, allowing the plating process to automatically adjust deposition rates based on local geometry. This enables high-quality plating in confined areas while maintaining appropriate plating characteristics on standard surfaces
2Manufacturing precision
If standard plating solutions are used, then the process is simple and cost-effective, but wettability issues prevent effective plating in confined areas
Solution Approach 1:
The patent incorporates pre-treatment steps that prepare the substrate surface before main plating. This preliminary action includes applying suppressor compounds that modify surface properties to enhance wettability and promote uniform copper nucleation in confined spaces, thereby achieving plating uniformity in micro-vias without significantly complicating the overall manufacturing process
3Manufacturing precision
If conventional plating baths are used, then mass transport is adequate for open surfaces, but mass transport limitations occur in confined spaces
Solution Approach 1:
The patent employs periodic or pulsed plating cycles that alternate between deposition and brief interruption periods. This periodic action allows copper ions to diffuse into confined spaces during deposition phases and prevents excessive heat buildup and additive depletion during interruptions, thereby maintaining consistent copper deposition in micro-vias and through-holes while preserving overall plating productivity
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 process ensures reliable copper plating in micro-vias and through-holes, improving wettability and mass transport, and achieving consistent plating results that meet industry specifications for miniaturized electronic components.
Implementation Method 1
electrolytic copper plating process comprising: 1. Contacting a surface with a pre-treatment solution comprising an aqueous solution of an anti-suppressor for copper electrochemical reduction... and then 2. Contacting said surface as a cathode with an electrolytic copper plating solution and applying a plating current such that copper is plated on the surface
Implementation Method 2
anti-suppressor for copper electrochemical reduction. The anti-suppressor is a sulfur containing organic compound comprising a sulfonate group or a sulfonic acid group
Data Source
AI summary
An electrolytic copper plating process comprising two steps is proposed. The process is particularly suited to plating in very confined spaces. The first step comprises a pre-treatment solution comprising an anti-suppressor that comprises a sulfur containing organic compound, preferably incorporating an alkane sulfonate group or groups and/or an alkane sulfonic acid. The second step comprises an electrolytic copper plating solution based on an alkane sulfonic acid.