Study Of Cl~--DPS-NP-n And Cl~--BSP-AEO-n Additive Series For High Performance Copper Foil

The development of science and technology requires the performance enhancement of electrolytic copper foil, and to produce high-performance electrolytic copper foil, excellent additives are needed. In view of the defect of industrial additives, this paper is devoted to the research and development of additive formulation without gelatin and dye in acid bright copper plating with simple composition and excellent properties. Copper electrodeposition process in present of additives and mechanism of action of additive components in the process were studied in this paper. The main research contents are as follows:1. Two series of acidic copper plating additives Cl--DPS-NP-n and Cl--BSP-AEO-n were studied. In addition to Cl--DPS-NP-10, Cl--BSP-AEO-10 and Cl--BSP-AEO-15, the rest of the additives were used to make bright and smooth electrolytic copper foil with roughness Ra﹤0.2 μm, Rz﹤2.0 μm and glossiness larger than 150 Gs. Research of these two additives series shows that with the increasing polymerization degree of NP-n(AEO-n), apparent properties of the coating are gradually improved, which shows that coating glossiness increases, roughness decreases and the surface defects disappear. For additive Cl--DPS-NP-15, orthogonal experiment and the single variable experiment were used to optimize additive formulation for improving apparent performance and mechanical performance of copper foil. Results show that, the best additive combination is Cl- 30 mg/L, NP-15 10 mg/L and DPS 4 mg/L under the acidic copper plating condition.2. Copper electrodeposition process with additive Cl--DPS-NP-15 was studied by linear sweep voltammetry and chronoamperometry. Results show that additive Cl--DPS-NP-15 shows the depolarization effect in the process and reduces the apparent activation energy of electrode reaction. Scharifker- Hills(SH) theory model and Heerman- Tarallo(HT) theoretical model were used to analyze experimental data, and the results show that Cl--DPS-NP-15 does not change the copper deposition mechanism of instantaneous nucleation with three-dimensional(3D) growth, but it can significantly reduce the copper nucleation density and increase the diffusion coefficient of copper ions, thus inhibiting copper crystal nucleus formation and promoting the growth of grains. SEM and XRD characterization of the copper foil indicated that additive Cl--DPS-NP-15 can significantly improve the leveling of coating, and reduce the texture coefficient of(220) crystal plane, and with it come(111) preferred orientation face.3. Adsorption morphology of NP(EO)n in electric double layer and its influence on electrodeposition process were studied by potential scan electrochemical impedance spectroscopy, linear sweep voltammetry and chronoamperometry. Results show the adsorption layer of NP(EO)n on electrode blocks the diffusion of Cu2+ enhances the cathode polarization and refines the grain size, therefore, NP(EO)n is used as brightener carrier in acidic copper plating. NP(EO)n has different effects on kinetic parameters of copper electrodeposition due to the different adsorption morphology of NP(EO)n on the electrode/solution interface. SEM and XRD characterization of copper foil indicated that grain size is not the only factor to affect the apparent performance of copper foil, and crystal orientation may also affect the morphology of copper foil.