Preparation Of Electrostatic Selfassembled Conductive Carbon Film Andstudy On Direct Electrodeposition Of Copper

At present, component interconnection between intra and inter layer are realized by copper conductive line and metallic holes on printed circuit boards(PCB), respectively. Traditional deposition process for non-metallic, electroless copper plating are applied after catalyzed colloidal palladium and electrodeposition. This complicated process required the use of precious metals palladium and harmful formaldehyde. With the rising demand for energy conservation and reduction of pollutant emissions, traditional manufacturing process was not suitable for continuous application. In this work, the formation of copper coating by direct electrodeposition on as-prepared carbon conductive film was proposed. Specifically, negatively charged carbon particles were electrostatical adsorpted to onto positively charged substrate surface with after treating with cationic surfactant by electrostatic force, and direct copper electrodeposition on self-assembled carbon film were studied. This new additive manufacturing method with high production efficiency and low pollutant emissions could replace electroless plating process, providing valuable guidance for the development of PCB manufacturing technology.Surfactants as dispersing agent in aqueous solution for carbon black were evaluated, it was found that nonylphenol polyethylene ether(TX-10) showed a better performance than five others, and the viscosity and transmittance reached the minimum by adding relative 25 wt.% of carbon black. From the perspective of wetting the model of surfactant adsorption on the surface of carbon black was established. The relationship between the morphology or structure of surfactant adsorption and adsorption energy was studied using molecular dynamics simulation software Material Studio(MS). TX-10 molecule in a supine position showed a largest adsorption energy on carbon surface. It also confirmed the results of the screening experiments. And then carbon black was dispersed in water with negative charge by adding nonylphenol polyoxyethylene alkylphenol ether phosphate(TXP-10) as the dispersing agent, which was synthesized by anionic modification of TX-10. UV visible spectroscopy confirmed that adsorption of carbon black dispersed by TXP-10 increased significantly after treating with cationic polyacrylamide(CPAM).Concentration and time and other factors that influence the self-assembly of carbon black film were investigated. The optimized preparation process was determined:the 10% cationic degree of CPAM, the concentration of 100mg/L. the processing time for 150 s, the concentration of carbon black dispersion including carbon black 1.0wt.% and TXP-10 0.25 wt.%, ball milling dispersion for 120 min, processing cycles for twice.By the experiment related to direct electroplating on t he self-assembled carbon black film, it was found that the adsorption of TXP-10 on conductivity carbon black surface increased the cathodic polarization of the copper deposition, resulting in reduced growth rate of copper on the carbon film. And the use of copper inhibitor and optimization of bath components can greatly increase the copper polarization, the polarization potential of carbon film deposition of copper is less than copper. Optimized bath components by adding inhibitor can greatly increase the p olarization of the copper deposition, and make the polarization potential on carbon film less than it on copper film. The largest potential difference of copper deposition to 70 m V was achieved at 30mg/L PEG10000 in the copper sulfate plating solution. The growth rate increased significantly, but the copper coating is not uniform and bright. After carbon black oxidation treatment, hydroxyl groups and other oxygen-containing functional groups on carbon black surface decrease adsorption energy with TXP-10, confirming desorption of TXP-10 on oxidized carbon black surface via MS simulation. The polarization of copper deposition on the carbon black film decreased, due to the TXP-10 desorption. Copper coverage up to 100% after plating for 20 min. Through hole with six kinds of pore sizes were treated by CPAM and oxidized carbon black dispersion, and uniform and complete copper coating with good adhesion was observed.Self-assembly of graphene oxide(GO) film was studied. First the effect of p H value on GO dispersion was discussed. It was found that graphene oxide was more fully dispersed at p H value of 10, corresponding to the lowest zeta potential(-68 m V). The positive correlation between characteristic peaks of absorbance and the number of the assembled layers reveal the same thickness of assembled GO film. Self-assembled GO film was reduced by constant potential polarization and sodium borohydride chemical reduction. Sodium borohydride reduced GO more efficient ly than potentiostatic electrochemical reduction, borohydride reduction reaction nearly completed after 20 min. Patterned conductive RGO/CPAM film were formed through self-assembly and chemical reduction on the PCB board surface, copper coating gradually growth along the RGO film from the current conducted end by constant current electrodeposition. The region of the conductive pattern within 20 min was completely covered with the copper film, producing a metallized film by direct electroplating.The interaction between GO and CPAM was studied. When GO nanosheets assembled on the CPAM surface the effect of static electricity was simulated by the electrochemical quartz crystal microbalance for the first time. It was confirmed that the intermolecular hydrogen bond was formed between arboxyl groups of GO and the amino group of CAPM as N-H...O: structure though the shift of absorption peak in the infrared spectrum and MS dynamics simulation.So two step s of self-assembly reaction was proposed: First, the electrostatic interaction was the driving force for self-assembly, GO under the influence of this attraction is close to CPAM adsorption layer. Next, GO is close to the CPAM layer, and intermolecular hydrogen bond was formed between carboxyl of GO and amino of CPAM. Finally, GO was fixed on the the surface of CPAM under electrostatic force, van der Waals force and hydrogen bonding interaction.