Adhesion Promoting Composition for Copper PCB Surfaces
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Solution Overview
Problem
The existing methods for improving adhesion between copper metal surfaces and polymeric materials in multilayer printed circuit boards are prone to delamination, especially due to the dissolution of copper oxide adhesion promoters in acidic media, leading to issues like the 'pink ring' phenomenon and inadequate bonding between dielectric and metallic copper layers.
Innovation Solution
A process involving an adhesion-promoting composition comprising an oxidizer, acid, corrosion inhibitor, source of halide ions, and mercapto propane sulfonic acid or bis-sodium sulfopropyl disulfide is used to treat the metal surfaces, creating a micro-roughened conversion-coated surface that enhances adhesion and acid resistance, thereby preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If copper oxide adhesion promoter coating is formed on copper surfaces, then adhesion between copper and polymeric materials is improved, but the copper oxide coating dissolves in acidic media causing pink ring formation and localized delamination
Solution Approach 1:
The patent applies preliminary action by treating the copper surface with a specific composition before the copper oxide is exposed to acidic media. The treatment composition is applied in advance to prepare the copper surface in a way that prevents subsequent dissolution, rather than attempting to fix the problem after delamination occurs.
Solution Approach 2:
The patent introduces an intermediary substance - a specific treatment composition containing hydrogen peroxide, acid, corrosion inhibitor, and halide ions - that acts as a mediator between the copper surface and the acidic environment. This intermediary layer protects the copper oxide from dissolution without preventing its adhesion-promoting function.
2Reliability
If copper surfaces are treated with chromic acid solution to stabilize copper oxide coating, then resistance to dissolution is improved, but the process complexity and environmental concerns increase
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the treatment solution. Instead of using chromic acid, the patent uses a composition with specific ratios of hydrogen peroxide, acid, corrosion inhibitor, and halide ions, changing the chemical parameters to achieve both stability and reduced complexity.
Solution Approach 2:
The patent employs a treatment composition that is simpler and potentially less expensive than chromic acid solutions. The composition uses more readily available chemicals and can be disposed of more easily, reducing both process complexity and environmental burden.
3Reliability
If copper oxide is reduced to metallic copper to eliminate pink ring formation, then acid resistance is improved, but adhesion between dielectric layers and copper deteriorates
Solution Approach 1:
The patent applies local quality by creating different properties in different regions or aspects of the copper surface treatment. The treatment composition selectively modifies the copper surface to provide both acid resistance and adhesion promotion, rather than uniformly applying a single treatment that can only achieve one objective.
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 proposed process significantly improves adhesion between metal and polymeric surfaces, maintains adhesion over time, and provides excellent acid resistance, effectively addressing the delamination issues in multilayer printed circuit boards.
Implementation Method 1
contacting the metal surface with an adhesion-promoting composition comprising: a) an oxidizer
Implementation Method 2
a source of halide ions; and at least one material selected from the group consisting of mercapto propane sulfonic acid, bis-sodium sulfopropyl disulfide, and mercapto propane sulfonate
Data Source
AI summary
An adhesion promoting composition and a process for treating metal surfaces with the adhesion promoting composition is described. The adhesion promoting composition comprises an oxidizer, an acid, a corrosion inhibitor, a source of halide ions and a material selected from a mercapto propane sulfonate, mercapto propane sulfonic acid, and bis-sodium sulfopropyl disulfide. The adhesion promoting composition increases the adhesion of polymeric materials to the metal surfaces and also provides increased acid resistance.