Development Status of Non-dye Acid Copper Plating Additives (2)

1.3 Polyethers and ether-based derivatives Polyethers are indispensable wetting agents in electroplating baths. Ether surfactants can enhance the cathodic polarization of baths and improve the leveling and wetting of the bath. MartinS [8,9] studied the effect of bisphenol A series ether derivatives on electroplating and found that derivatives with three ether groups can improve the coating ductility and leveling. Kuznetsov VV et al. [10] performed electrochemical studies on a series of crown ether plating additives in a three-electrode electrolytic cell with isolated cathode and anode compartments. Silver chloride silver was used as a reference electrode and crown ethers were found The agent splits first and plays a key role in the deposition kinetics.
1.4 Other Additives There are many reports on additives at home and abroad, and have been used in production to obtain better results.
Hainan University of Science and Technology [11] synthesized modified chitosan, and Xiangtan Mining Institute and Tianjin University [12] jointly developed copper sulfate plating additive TDY. Yixing Xinxin Rare Earth Applied Technology Research Institute [13] was used in bright acid copper plating. The introduction of rare earth additives has provided a reference for the further study of electroplating additives. Among them, the rare earth additive resists plating color change, because the copper layer is generally an intermediate and is rarely used in actual production. Wenzhou Gaote Chemical Co., Ltd. [14] adopts the intermediates of American PMC Group Raschig. The GT 210 acid copper plating brightener produced through strict combination emits fast light, good flatness and low current density area, and has a good range of gloss. Applications.
There are many reports of alkyl sulphonic acid as a brightener in foreign countries. Douglas WM uses methane sulphonic acid and bis-pyridine as brighteners, and has a deep deposition ability on high aspect ratio substrates; Nicholas MM [16] uses a series of alkyl sulphides. Acid as a brightener, found that it can greatly reduce the surface tension. RogerBF [17] obtained a good coating by increasing the polarization potential of an alkoxydiamine, a urethane, and an imidazoline-based compound by appropriate proportioning. WangQM [18] used a sulfhydryl-containing water-soluble organic substance as a brightener for copper plating and advanced interconnect metallization. ObengJS [19] used acetyl thioacetate as a brightener for integrated circuits and achieved good results.
The above additives are basically focused on the special requirements of the plating, the intermediates discussed above are generally used for the plating of the middle layer.
1.5 New dye-free additives - EPI
EPI series acidic copper additive consists of opener, supplement and auxiliary agent. The bath is a high copper and low acid solution, in which the chloride ion content is half of the chloride ion content in the dye type acidic copper plating.
Because EPI series do not contain dye molecules, it overcomes the disadvantages of dye system pyrolysis, is suitable for wide temperature operation, and there is no dye molecules entrapped in the coating, which reduces the internal stress of the coating compared with the dye type, and can obtain a soft coating. In addition, EPI also provides a smooth coating on plastic substrates. EPI system coating brightness, leveling, bath stability and other performance indicators can compete with the existing best dyes Atotech 510, especially the balance of a variety of additives is particularly prominent, but the EPI The lower zone is slightly inferior to the Atotech 510.
The copper plating layer of EPI is used as an intermediate layer, and the pretreatment before entering the next process is simple, economical and quick, and has considerable application value.

2 Outlook With the further development of additive-free copper acid additives, better and more perfect additive formulations will surely be formulated. Dye molecules contain benzene rings, N, S, O and other heteroatoms or heterocyclic compounds, such as phenazine, a new compound. From the perspective of the various formulations currently used, it is still more desirable to obtain better results from the compounding of multiple substances. However, the multi-additives have a problem of unbalanced proportions in the electroplating process, so the compounding ratio and supplementation amount are critical, while the single additive does not have this problem.
At present, the most important thing is to find the ideal medium-low brightener, especially low-level brighteners. For example, phenazine dyes in Atotech 510 can increase the lightness in the middle and low levels, but the excess will make the low-end shrinkage and the dye molecules stress the plating layer. Greater impact. Therefore, the substance that is to replace the phenazine dye may have the above characteristics at the same time, but it cannot be a dye substance so as not to increase the internal stress, and at the same time, it is also required to raise the plating power to a new level.
[references]
[1] Zhu Qiongxia, Yang Fuguo. Application of Organic Additives in Acidic Bright Copper Plating Process[J].Anhui Chemical Industry,2000(2):24.
[2] Huang Ling, Zhang Rui, Min Min, et al. The initial behavior of copper electrodeposition on glassy carbon electrode [J]. Electrochemistry, 2002, 8 (3): 263 ~ 268.