Effect of additives on microstructure and properties of the coarsened layer of very low profile (HVLP) copper foil

Additives are a cost-effective method to improve the performance of the very low profile (HVLP) copper foil coarsened layer. In this paper, the effects of 3,3’-Dithiobis-1-propanesulfonic acid disodium salt (SPS), gelatin, and sodium thiazoline dithiopropane sulfonate (SH110) concentration on the morphology, roughness, and peel strength of HVLP copper foil was reported. The results show that SH110 contributes significantly to the reduction of copper foil roughness, improvement of peel strength, and refinement of coarsened layer grains. In addition, the linear scanning voltammetry and AC impedance spectroscopy of the solution were carried out to understand the action mechanism of additives on the copper foil surface. The results demonstrate that SPS promotes the copper deposition process due to the presence of sulfonic acid groups(–SO 3 ). The amino group(–NH 2 ) of gelatin inhibits copper deposition. SH110 has both promoter (Sodium 3-Mercapto-1-Propane Sulfonate, MPS) and inhibitor (Tetrahydrothiazolidinone, H1) fragments, which achieve synergistic or competitive effects consistent with the composite additive. Graphical abstract