Synthesis of coplanar quaternary ammonium salts with excellent electrochemical properties based on an anthraquinone skeleton and their application in copper plating

• Four anthraquinone-based levelers agents designed and synthesised for the first time. • First quantitative and qualitative analysis of the effect of planar effects on levelers. • Quantitative analysis of the leveling agent's ability to persist after adsorption at the electrode by electrochemical testing (Tafel). • The electrostatic potential, average localised ionisation energy and polarisation rate are used to analyse the levelling mechanism of levelers.. Through-hole copper deposition technology for nano-micro hole printed circuit boards (PCBs) is of great importance in the electronic industry. Achieving efficient copper electrodeposition using trace amounts of plating additives is a very challenging problem. Here, four anthraquinone (AQS) quaternary ammonium salts have been synthesised based on anthraquinone yellow pigments. These four compounds were functionalised for the first time as promising levelers for through-hole copper electrodeposition. Electrochemical tests, theoretical calculations and Molecular dynamics simulation demonstrate that the AQS-Qnl compounds have the most excellent copper deposition inhibition and electrode adsorption capacity among the four compounds. TP value measurement, SEM, XRD tests confirmed that AQS-Qnl can actually have high through-hole filling and excellent levelling performance in practical PCB plating. Based on this, The levelling mechanism of AQS-Qnl leveler was analysed by using electrostatic potential, average local ionisation energy and polarisation rate and the mechanism of AQS-Qnl's interaction with PEG and SPS in practical plating was proposed using galvanostatic measurements.