Abstract:Polyethylene glycol（PEG）is a commonly used wetting agent in the preparation of electrolytic copper foil, which can refine the grain, smooth the coating, and adjust the mechanical properties of the coating. There are many studies on the effect of PEG concentration on the properties of electrolytic copper foil in the existing literature, but there are few reports on the effect of PEG molecular weight on the properties of electrolytic copper foil. In this stduy, polyethylene glycol（PEG）with molecular weight of 200, 1000, 4000 and 8000 is used as the additive of electrolytic copper foil. In the presence of Cl-, electrolytic copper foil with PEG of different molecular weight is prepared by electroplating process. The effects of PEG molecular weight on copper electrodeposition behavior, surface appearance, mass weight and thickness, M-surface brightness and roughness, tensile strength and elongation were investigated. The results show that when the molecular weight of PEG is 200, the electrodeposition of copper is promoted, Compared with the electrolytic copper foil without PEG, the surface grain size is slightly larger, the roughness is increased, and the tensile strength and elongation are decreased. When the molecular weight of PEG is increased to 1000, 4000 and 8000, the electrodeposition of copper is inhibited, and the inhibition effect is 4000＞1000＞8000. At this time, the surface grain size of the prepared copper foil decreases and becomes flat and uniform, the roughness decreases, and the tensile strength and elongation also increase. Especially when the PEG molecular weight is 4000, the performance of the prepared electrolytic copper foil is the best, the M-surface roughness decreases from 3.79 to 2.79, and the tensile strength and elongation increase by 43% and 114%, respectively. PEG with different molecular weight has little effect on the mass weight, thickness and M-surface brightness of copper foil. The results of this study provide a reference for the selection of appropriate molecular weight PEG in electrolysis of copper foil.
