Research On Compound Additives Used For Copper Electroplating On Printed Circuit Board

Printed Circuit Board(PCB) acid copper electroplating is an important way to achieve hole metallation, which requires the electrolyte has high throwing power, additives play an important role on determining the electrolyte's throwing power. This study was designed to develop high performance additives to meet the requirements of PCB with a high aspect ratio. According to the polarization theory and the synergy among the additives, the influence of the types and the structures and the concentration of additives on throwing power were researched, and the mechanism of additives were discussed.In accordance with the mechanism and structure, organic additives of acid copper for plating PCB generally are divided into accelerators, inhibitors and levelers. In the form of accelerator-inhibitor-leveler, the selected additives were combinated into eleven different systems. By inner-hole method, CJJ was employed as the accelerator, and PEGb was the inhibitor, JAY1 and JAY2 were levelers. The throwing power of CJJ-PEGb-JAY1 and the CJJ-PEGb-JAY2 on PCB with an aspect ratio of 10 were respectively 44.4% and 53.3%. So, the CJJ-PEGb-JAY2 system was determined as the best system. The optimal concentration of CJJ, PEGb and JAY2 were respectively 0.001g/L, 0.100g/L and 0.020g/L through the single factor experiment. The throwing power of the optimized system came at 73.0%, increasing 19.7% compared with the system free of optimizing. The optimized system markedly improved the current density distribution infthe microvia, which greatly enhanced the deposition of copper film in the middle of the microvia.The cathode polarization tests showed that the greater the polarization of the electrolyte, the higher the throwing power. The accelerator can make grain refinement and increase the brightness of the copper film; the inhibitors could make polarization significantly increased by adsorbing in the cathode surface; the levelers adsorb on the high current density areas and effectively inhibit the deposition rate of copper film to improve the current density distribution in the microvia. When the thiazoline-base was added into SPS, it increased the polarization of the electrolyte. It was easier for the leveler containing quaternary ammonium to adsorpt in the cathode surface, whose polarization effect was stronger than nitrogen heterocyclic compounds'. Accelerators, inhibitors and levelers were in favor of incrasing the polarization in the condition of single composite, inhibitors had the biggest influence on the polarization among these components. What's more, Cl- could affect the polarization of the various components. The open circuit potential~time curve indicated that in the presence of PEG, CJJ reduced the polarization; PEGb and JAY2 had a good synergy with eath other.