采用背光级数、SEM及能谱分析等方法研究了阳离了表面活性剂聚季铵盐对印制线路板(PCB)碱性除油工艺的影响。结果表明,不加聚季铵盐时,碱性除油后,PCB孔壁镀层裸露出较多的玻璃纤维基材,镀层漏光现象严重,背光级数仅为6级。随聚季铵盐加入量增大,PCB孔壁背光级数及化学镀速均先增大后减小,当浓度为13.5mL/L时,孔壁镀层鲜见玻璃纤维,背光实验几乎不透光,级数高达10级。聚季铵盐主要作用为将PCB基体调整为荷正电,以促进后续胶体钯活性粒子的吸附,同时吸附在油/溶液界面上,降低界面张力,加强碱液对PCB孔壁的润湿性,此外,它还是OH的主要提供者,实现去除PCB孔壁油污的作用。
The influence of cationic surfactant polyquaternium on alkaline degreasing process of the printed circuit board (PCB) was evaluated by means of the examinations of the backlight degree, SEM and EDS after that the degreased PCB was Cu-deposited. The results show that polyquaternium has a significant influence on the alkaline degreasing process. Glass fiber could be observed on the surface of the Cu-deposited PCB hole after alkaline degreasing in polyquaternium- free bath, and the backlight level was only 6th grade due to the serious light leak. The electroless deposition rate and the backlight degree of the Cu-deposited PCB first increased and then decreased with the increase of polyquaternium concentration in alkaline degreasing bath. When the dosage reaches 13.5 mL/L, glass fiber is rare to be seen on the hole wall, and the backlight level reaches the highest of 10th grade. The polyquaternium not only adjusts the electric charge on substrate, which promotes the adsorption of active colloid palladium particles, but also reduces the interfacial tension and enhance the wettability of alkali solution to the surface of PCB hole. Besides, polyquaternium is the main source of OH-, and as a result the oil is removal from PCB hole-wall.