2-Aminobenzimidazole (2-AB) is primarily utilized in agriculture and medicine for its bactericidal, anti-inflammatory, and anticancer properties, and it is generally not classified as an environmentally hazardous or toxic substance. Research on 2-AB in corrosion inhibition remains scarce, and its application in super-roughening processes has yet to be explored. This study investigates the enhancement effect and underlying mechanism of 2-AB as a corrosion inhibitor on the interfacial adhesion between copper substrates and epoxy resin during the super-roughening process in printed circuit board (PCB) manufacturing.
Copper-resin composites are prepared using weight loss measurements, spray etching, and vacuum hot pressing. Weight loss tests are conducted to quantify the corrosion efficiency of etching solutions containing varying 2-AB concentrations. A spray method is applied to produce uniformly etched copper foils for surface characterization and subsequent vacuum hot pressing, while vacuum hot pressing ensured homogeneous bonding between copper and resin. Pull-off strength tests are conducted according to IPC (Association Connecting Electronics Industries) standards with three valid samples per group, to directly evaluate adhesion improvement—a critical metric for super-roughening efficacy. The micro-mechanisms of adhesion enhancement are analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and electron back scatter diffraction (EBSD), focusing on surface morphology, roughness, and selective corrosion behaviors. Potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) tests further validate 2-AB's corrosion inhibition effectiveness and mechanisms in acidic cupric solutions.
Weight loss tests revealed that the addition of corrosion inhibitors reduces the corrosion rate of the etching solution, with 1-aminobenzotriazole, a structural analog of 2-AB, exhibiting higher corrosion inhibition efficiency. Notably, this work directly evaluates the adhesion enhancement effect of corrosion inhibitors through pull-off strength testing, a methodology rarely reported in existing literature. Pull-off strength tests demonstrate that under 2-AB treatment, the copper-resin adhesion reaches a maximum of 14 kN/m, more than doubling the adhesion strength achieved with its analog 1-aminobenzotriazole. This indicates that corrosion inhibition efficiency alone is insufficient to predict adhesion enhancement. SEM analysis shows that 2-AB promotes the formation of surface structures on copper that favor adhesion, significantly increasing the contact area between copper and resin. EBSD results further reveal that the Cu (001) crystallographic plane dominates the surface of these adhesion-enhancing structures, with its proportion substantially higher than other crystallographic orientations. This suggests that the formation of adhesion-promoting structures relies on selective protection induced by 2-AB. Potentiodynamic polarization and EIS tests demonstrate that the corrosion inhibitor exhibits suppression effects on metal corrosion when the self-corrosion current density decreases, charge transfer resistance decreases, and double-layer capacitance simultaneously reduce. However, the microscopic defects in the adsorption layer prevent the inhibitor from forming a complete coverage on the metal surface, resulting in preferential adsorption on localized region. This incomplete coverage accelerates localized corrosion in unprotected areas, thereby increasing surface roughness. The enhanced roughness promotes mechanical interlocking at the Cu-resin interface, ultimately improving the adhesion strength.
This study proposes that 2-AB, as a corrosion inhibitor in the super-roughening process, can significantly enhance the interfacial adhesion between copper and resin. In terms of adhesion enhancement, under the action of a single corrosion inhibitor, an adhesion strength of 14 kN/m is achieved. From the perspective of surface morphology, 2-AB modifies the copper surface to form a robust structural foundation that supports the improved copper-resin interfacial adhesion. Regarding practical applications, 2-AB exhibits excellent chemical stability. More importantly, the etching rate of the solution containing 2-AB remains largely unaffected, enabling rapid surface modification within a shorter time frame, thereby demonstrating high suitability for industrial-scale production. From an environmental and economic standpoint, 2-AB offers notable cost-effectiveness and environmental friendliness, further enhancing its industrial applicability.
Key words
2-Aminobenzimidazole /
copper /
surface adhesion strength /
corrosion inhibitor /
super roughening /
surface modification
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