Study of Iron Impurity Removal by TTHA in High-Speed Tin Plating

The feasibility to remove iron impurity by triethyl-tetra-amine-hexa acetic acid(TTHA) in high-speed tin plating was investigated,which was aiming at eliminating the negative effect caused by the ferrous ions impurities.The content of Fe(Ⅱ) in the coating was determined by means of X-ray fluorescence spectroscopy.The morphology of the coating was observed using an optical microscope and an atomic force microscope,and the action mechanism of the TTHA in the electrodeposition process was discussed as well.It was found that HHTA was able to effectively eliminate the negative effect caused by the iron impurity and remarkably improve the coating quality.The reason lay in that TTHA was capable of eliminating the interference caused by iron(Ⅱ) by way of chelating effect and taking part in the electroplating process.