Metal Surface Adhesion via Acid Post-Dip Treatment
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Solution Overview
Problem
The existing methods for improving adhesion between polymeric materials and metal surfaces in multilayer printed circuit boards face challenges such as insufficient bonding strength, delamination due to copper oxide dissolution during metallization, and phase boundary separation, which are not adequately addressed by previous techniques.
Innovation Solution
A process involving an adhesion-promoting composition followed by an acid post-dip treatment to create a microroughened metal surface, enhancing adhesion between the metal and polymeric materials without additional processing steps, specifically using hydrogen peroxide, mineral acids, corrosion inhibitors, and optionally halide ions and water-soluble polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If copper oxide adhesion promoter coating is applied on copper surfaces, then adhesion between circuitry innerlayers and dielectric substrate layers is improved, but the copper oxide coating is dissolved during through-hole metallization process, leading to localized delamination
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesion promoter by using a specific copper oxide forming composition containing chlorite and caustic, and subsequently treating with sulfuric acid to create a red oxide layer with controlled properties that resists dissolution during metallization
Solution Approach 2:
The patent applies the copper oxide adhesion promoter coating on the copper surfaces of circuitry innerlayers before assembling them with pre-preg layers, and further treats with sulfuric acid to create a protective red oxide layer that prevents dissolution during subsequent through-hole metallization processing
2Reliability
If thicker copper oxide coating is applied to retard dissolution, then resistance to dissolution is improved, but adhesion promotion effectiveness is reduced
Solution Approach 1:
The patent optimizes the thickness and composition of the copper oxide layer by controlling the oxidizing treatment parameters and subsequent sulfuric acid treatment, creating a thin but highly effective red oxide layer that provides both adhesion promotion and dissolution resistance
Solution Approach 2:
The patent creates a composite structure consisting of the copper substrate, copper oxide adhesion promoter layer, and red oxide protective layer, where each layer serves a specific function: copper provides conductivity, copper oxide provides adhesion promotion, and red oxide provides dissolution resistance
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 process significantly increases adhesion values, reduces the likelihood of delamination, and prevents the formation of pink rings, providing a stable and reliable bond between metal and polymeric surfaces, particularly in multilayer printed circuit board manufacturing.
Implementation Method 1
contacting the metal surface with an adhesion-promoting composition... which involves an oxidizer, an acid, a corrosion inhibitor and a quaternary ammonium surfactant
Implementation Method 2
treating the metal surface with an acid post-dip composition to provide a microroughened metal surface
Data Source
AI summary
A process for treating metal surfaces that includes first contacting the metal surface with a particular acidic peroxide adhesion promoting composition, followed by contacting that metal surface with an aqueous acid post-dip composition to provide a micro-roughened surface. This treatment is particularly suitable for treating metal surfaces used in printed circuit multilayer construction.