PCB铜基表面非钯活化化学镀镍的研究

印刷电路板(PCB)铜线路借助钯活化的化学镀镍法不但价格昂贵,而且容易造成溢镀,因此开发非钯活化的化学镀镍工艺具有重要意义。以硫脲为铜的强配位剂,通过降低铜电极的电极电位,开发出了先在铜表面置换预镀薄镍层、再自催化化学镀镍的新工艺。镀镍工艺流程为除油、除锈、微刻蚀、预镀镍、激活、化学镀镍。扫描电镜(SEM)观察显示得到的镍镀层平整、均匀、致密。EDS谱分析结果显示镀层主要由镍和磷组成,含量分别约为92%和6%,X射线荧光衍射仪(EDXRF)测得镀层厚度为5.95μm,镀层的沉积速率约为14.19μm/h。镀层与基体结合力良好,后续镀金层在镍镀层上附着力良好。

Electroless Nickel Plating with Non-Pd-Activation on the Cu Surface of PCB

In PCB field,Pd-activation is usually required to initiate the electroless Ni plating on Cu circuits.It increases cost and sometimes causes some defects.Therefore,the development of direct electroless Ni plating on Cu without Pd-activation is significant.Thiourea has been chosen as the specific complex.A new technology for electroless nickel plating (first replacement of pre-plated thin Ni layer and then autocatalyric electroless nickel) was developed on the Cu surface by reducing the deposition potential using thiourea.Technological process of electroless nickel plating was as follows:degreasing,acidic derusting,microetching,pre-nickel plating,electroless nickel plating.The surface morphologies,microstructure and composition of the film were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS),respectively.Results showed that the film thickness was approximately 5.95 μm,and the deposition rate of Ni film was approximately 14.19 μm/h.Besides,the Ni film had good adhesion on the Cu substrate and the following plating film adhered to the Ni film well.