碱性除油液中OP-10乳化剂浓度对印制线路板孔壁化学镀铜性能的影响

Influence of Emulsifier on Alkaline Degreasing Effectiveness and Properties of Electroless Copper Coating of Hole-Wall of Print Circuit Board

印刷线线路板(PCB)孔壁化学镀铜金属化前的碱性除油处理,有利于调整其电荷和后期的催化化学镀铜反应。采用背光级数、SEM及EDS等方法研究了碱性除油液中OP-10乳化剂浓度对PCB孔壁化学镀铜性能的影响。结果表明,OP-10浓度对PCB的碱性除油有显著影响:不加OP-10,PCB孔壁化学铜镀后基材裸露较多,漏光现象严重,背光级数仅为6级;随OP-10浓度的增大,PCB孔壁镀铜层的背光级数及镀速均先增大后减小,当其为2.5 mL/L时,镀铜层几乎全部覆盖基体,背光级数高达9.5级;OP-10的主要作用是吸附在油污与溶液界面处,降低界面张力,加强碱液对PCB孔壁的润湿,去除其上的油污,确保后续化学镀铜的成功。

OP-10 emulsifier was introduced into the alkaline degreasing bath of print circuit board(PCB) to remove various pollutants and adjust electric charge on the surface of PCB hole-wall before electroless plating.The effects of OP-10 emulsifier on the alkaline degreasing effectiveness of hole-wall of PCB and the properties of electroless Cu coating thereon were investigated based on measurement of backlight degree as well as observation with a scanning electron microscope and determination with an energy dispersive spectrometer.It was found that the OP-10 emulsifier had significant effects on the alkaline degreasing effectiveness of PCB and the properties of electroless Cu coating thereon.Namely,in the absence of the emulsifier,discontinuous Cu coating was formed on the hole-wall surface of PCB,and serious light leaking was observed in association with a 6th level backlight degree of PCB.Besides,both the backlight degree of PCB and deposition rate of electroless Cu coating initially rose and declined later with increasing concentration of OP-10 emulsifier in alkaline degreasing bath.When the concentration of OP-10 emulsifier in the alkaline degreasing bath was kept as 2.5 mL/L,the PCB substrate was almost completely covered by the electroless Cu coating,and the backlight degree of PCB in this case was raised to the highest 9.5th level.This might be because OP-10 was adsorbed at the oil-solution interface to reduce the interfacial tension and enhance the wettability of alkali bath on the hole-wall surface of PCB,thereby resulting in improved degreasing effectiveness.