Surface modification of epoxy resin by MnO2–H2SO4–H2O–Na4P2O7 for enhanced adhesion to electroless copper

Abstract

The purpose of this study was to enhance the adhesion strength between the epoxy resin (EP) substrate and the electroless copper plating layer by utilizing a MnO2–H2SO4–H2O–Na4P2O7 system for surface modification. The effect of the volume ratio of VH2SO4:VH2O and the duration of surface modification on various surface characteristics and adhesion strength was examined. The results provide valuable insights into the relationship between these factors and their impact on the properties of the surface. Optimal results were achieved with a volume ratio of VH2SO4:VH2O at 3:1, a surface modification time of 20 min, Na4P2O7 content of 30 g L−1, and a modification temperature of 50 °C. Following the surface modification treatment, the EP substrate surface exhibited many deep micro-holes, significantly improving surface roughness. Due to the enhanced roughness on the surface and the application of suitable modifications, the contact angle on the EP substrate surface exhibited a significant decrease from 94.6° to 19.5°. This alteration caused the surface to transition from hydrophobic to hydrophilic. The adhesion strength between the EP substrate and the electroless copper plating layer was significantly increased to 0.74 kN m−1. This improvement was attributed to the combined effects of surface roughness and hydrophilicity of the substrate surface.