Investigation on synthesis and mechanism of a Sudan Ⅰ copper electrodeposition leveler based on influencing ion diffusion strategy

A series of quaternary ammonium salt derivatives based on 1-phenylazo-2-naphthol (Sudan I) have been synthesized and showed novel ability in inhibiting copper electrodeposition as efficient levelers. The electrochemical test, theoretical calculation and molecular dynamics simulation were presented, and Sudan-QNL exhibited the best ability to adsorb electrode and promote polarization. The microscopy and X-ray diffractions showed that Sudan-QNL can significantly improve the flatness and filling of copper electrodeposition in the printed circuit board (PCB) through hole. Through the observation of copper layer by electron backscatter diffractometer (EBSD) and X-ray diffractometer (XRD), it was found that the addition of additives can significantly refine the grain size and obtain a smooth deposited copper layer with high preferred orientation of the crystal plane. In addition, the high electrostatic adsorption of levelers and its strong binding ability to copper ions and thus affecting the ion diffusion rate may be the fundamental reasons for its role. [Display omitted] •Five new levelers based on Sudan Ⅰ have been synthesized.•Systematical studies of relationship of crystal plane orientation and copper coating.•Mechanism of Sudan-QNL levelers based on influencing ion diffusion rate was proposed.•Effective leveling component is decomposition products of Sudan-QNL.