Investigation of Through-Hole Copper Electroplating with Methyl Orange as A Special Leveler

Abstract

Methyl Orange (MO) with two kinds of functional groups can act as both an accelerator and an inhibitor, which has been used as a special leveler to simplify the electroplating additive system in the through-hole (TH) copper electroplating experiments. In this work, the role of MO in TH electroplating is characterized by molecular dynamics simulations and quantum chemical calculations. It is suggested that MO can spontaneously flatten the copper surface and be well adsorbed on the cathode surface, which inhibit the copper electrodeposition on the cathode. Electrochemical behavior of MO was evaluated by galvanostatic measurements (GM) and cyclic voltammetry (CV) to confirm that MO hardly affects the potential due to its duel functions of depolarizing and polarizing effects from the molecular structure of sulfonic acid group and other groups to achieve the internal Cu²⁺ reduction acceleration and mass transfer inhibition. Throw power value of TH with the aspect ratio of 10:1 could reach 92.34% from the base plating solution bath with the additions of only EO/PO and MO. The study of MO could provide new ideas for the development of electroplating additive system.

Keywords

copper electroplating / through-hole / additive / methyl orange

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