挠性印刷电路板用超低轮廓铜箔的表面处理工艺

Surface treatment process of very-low profile copper foil for flexible printed circuit boards

研究了挠性印制电路板（FPC）用超低轮廓（VLP）电解铜箔的表面处理工艺。在硫酸铜与硫酸的混合电解液中,以连续旋转鼓状钛筒为阴极,在50-80 A/dm2的电流密度下电沉积得到12μm厚的铜箔,再以（20±0.1）m/min的速度对铜箔进行表面处理：在其光面进行分形电沉积铜,然后电沉积纳米锌镍合金,再经过三价铬钝化处理并涂覆一层硅烷偶联剂。处理后的铜箔光面呈黑色,粗糙度为1.2-2.0μm,毛面粗糙度≤2.5μm,不含铅、汞、镉、砷等有害元素,具有优异的抗剥离强度以及抗氧化、耐腐蚀和蚀刻性能,可以替代同类型的进口铜箔,应用于FPC制作和高密度互联（HDI）内层板等。以该工艺生产的VLP铜箔已在FPC生产厂家获得应用。

The surface treatment process of very-low profile（VLP） electrolytic copper foil used for flexible printed circuit（FPC） boards was studied.The copper foil with a thickness of 12 μm was prepared in an electrolyte containing copper sulfate and sulfuric acid over a current density range of 50-80 A/dm2 with a continuous rotary titanium drum as cathode.The smooth surface of the copper foil was treated by the following steps successively at a speed of 20 m/min： copper plating,nano-Zn–Ni alloy plating,trivalent chromium passivation,and coating with silane coupling agent.The treated copper foil has a black smooth surface with a roughness of 1.2-2.0 μm,and a matte side with a roughness of ≤2.5 μm.The copper foil has excellent anti-peel strength and resistance to oxidation,corrosion and etching but without harmful elements such as Pb,Hg,Cd and As,and can be served as an alternative for the same type of imported copper foil for application to manufacturing FPC and HDI（high-density interconnection） inner layer.The VLP copper foil prepared by the process has found application in FPC manufacturers.