Theoretical Research and Application of Additive DPS in the Electrochemical Microroughening Layer of Copper Foil

The roughening layer on the electrolytic copper foil is crucial to the performance of printed circuit boards (PCBs). Additives provide a straightforward and efficient method for improving the performance of the copper foil roughening layer. This study introduces N,N-dimethyl-dithiocarbamate propanesulfonate (DPS) for the first time as an electrochemical roughening additive for copper foils. The effect of DPS concentration on roughening morphology and copper deposition was investigated using techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). In addition, density functional theory (DFT) calculations, in situ Raman spectroscopy, and electrochemical quartz crystal microbalance (EQCM) were employed to examine the adsorption interactions between DPS, the copper substrate, and copper ions. At a concentration of 20 mg/L, the copper foil roughening layer exhibited significant improvement in morphology, resulting in the successful preparation of a high-volume low-profile (HVLP) copper foil. The roughening layer achieved an R_Z value as low as 1.09 μm and a peel strength of 1.02 N/mm.