化学置换镀钯的研究

Research on chemical immersion palladium process

分别运用X射线荧光测厚和SEM,研究了Pd浓度、NH3·H2O浓度、EDTA浓度、pH值及时间对印刷电路板置换镀钯的影响。实验结果表明,当CPd2＋浓度在0.5~0.8g/L范围内,钯的沉积厚度随钯离子浓度的增加而增加;当CPd2＋浓度大于0.8g/L时,钯的沉积厚度基本不变;Pd的沉积厚度随着所加入的NH3·H2O的量的增多而先增大后减小;EDTA能提高镀钯液的稳定性,Pd的沉积厚度随着EDTA浓度的增加而降低;当pH=（5.0±0.2）时,Pd的沉积厚度达到最大;镀钯速率随施镀时间的增加而下降。SEM的结果表明,在40℃时所得钯层致密、厚度均匀。

The effects of Pd concentration,NH3·H2O concentration,EDTA concentration,pH and immersion time on chemical immersion palladium process on printed circuit board by using X-ray fluorescence for thickness measuring and SEM were investigated.The results showed that when the Pd ion concentration was from 0.5g/L to 0.8g/L,the Pd deposition thickness increased with the increasing of the Pd ion concentration;when the Pd ion concentration was greater than 0.8g/L,the Pd deposition thickness was almost the same.The sedimentary thickness of the Pd with the joining of NH3·H2O quantity first increase then decrease;EDTA can improve the stability of the palladium plating liquid and the sedimentary thickness of the Pd decreased with the increase of the EDTA;when pH=5.0±0.2,the Pd deposition thickness reached the maximum.The plating speed decreased with the increasing plating time.The characterization results of SEM indicated that the Pd coating was compact and uniform at 40 ℃.