Novel Electroless Plating Copper Additives for Sodium Hypophosphite System and Its Effect on the Properties of Plating Bath and Coating

LI Li-qing, FENG Luo, WU Pan-wang, WU Jing-jie, HUANG Zhi-qiang, XU Yong-zhang, YANG Jia-qi, JI Shu-rui

Surface Technology ›› 2020, Vol. 49 ›› Issue (7) : 329-337.

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Surface Technology ›› 2020, Vol. 49 ›› Issue (7) : 329-337. DOI: 10.16490/j.cnki.issn.1001-3660.2020.07.041
Coating Material and Technology

Novel Electroless Plating Copper Additives for Sodium Hypophosphite System and Its Effect on the Properties of Plating Bath and Coating

  • LI Li-qing1, FENG Luo1, WU Pan-wang1, HUANG Zhi-qiang1, YANG Jia-qi1, JI Shu-rui1, WU Jing-jie2, XU Yong-zhang3
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Abstract

The work aims to apply polyvinyl pyrrolidone and diphenylaminesulfonic acid sodium to the electroless copper plating system of sodium hypophosphite as additives, and to obtain the process and condition of the optimum application results. Based on PCB epoxy resin board, the electroless copper plating system of sodium hypophosphite with polyvinyl pyrrolidone and diphenylaminesulfonic acid sodium as additives and its performance were investigated by the electrochemical method. The effect of additives on deposition rate was studied by heavy method; the effect of additives on the surface quality was analyzed by SEM and EDS; the effect of additives on the surface porosity was studied by the polarization curve method; the effect of additives on the corrosion resistance was studied by AC impedance; and the stability of plating solution was also measured. The results show that, when pH=10 and at 65 ℃, both polyvinyl pyrrolidone and diphenylaminesulfonic acid sodium had good properties for electroless copper deposition in base solution including CuSO4 5 g/L, NaH2PO2 30 g/L, Na3C6H5O7?2H2O 16 g/L, H3BO3 30 g/L, NiSO4 1 g/L, and their best dosages were 20~28 mg/L and 50~58 mg/L respectively. When used polyvinyl pyrrolidone and diphenylaminesulfonic acid sodium as combined additive in the range of their best dosage, the plating solution was more stable, the porosity of the coating was low, the corrosion resistance was good, the surface was uniform, and the copper content on the surface was up to 95.52%. Furthermore, the coating was pink and the deposition rate was in the range of 1.5~ 2.5 μm/h, which all met the requirements of PCB industry. Therefore, the best novel electroless copper deposition solution are that, CuSO4 5 g/L, NaH2PO2 30 g/L, Na3C6H5O7?2H2O 16 g/L, H3BO3 30 g/L, NiSO4 1 g/L, polyvinyl pyrrolidone 20~28 mg/L, diphenylaminesulfonic acid sodium 50~58 mg/L when pH=10 and at 65 ℃. The research results are of great significance to the development and application of electroless copper deposition additives.

Key words

sodium hypophosphate; electroless copper deposition; polyvinyl pyrrolidone; diphenylaminesulfonic acid sodium; porosity; corrosion resistance

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LI Li-qing, FENG Luo, WU Pan-wang, WU Jing-jie, HUANG Zhi-qiang, XU Yong-zhang, YANG Jia-qi, JI Shu-rui. Novel Electroless Plating Copper Additives for Sodium Hypophosphite System and Its Effect on the Properties of Plating Bath and Coating[J]. Surface Technology. 2020, 49(7): 329-337

Funding

Supported by China Postdoctoral Science Foundation (2016M592118), National Natural Science Foundation of China (21406097, U1607108), Postdoctoral Science Foundation of Jiangxi Province (2015KY11, 2015RC17) and Educational Commission Foundation of Jiangxi Province of China (GJJ190424)
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