Research On System Of High Deposition Rate And Stability Electroless Copper Plating

As a kind of material surface metallization techniques, electroless copper plating was widely applied to different fields because of its advantages, such as simple process operation, low cost, wide applicable material, however, the deposition rate and stability of the plating solution is very important for the application of the electroless copper plating technology to the practical production. Based on the solution-type catalyst ink without palladium, the effects of electroless copper plating solution composition and process conditions on the deposition rate and stability was studied in this thesis to obtain a kind of electroless copper plating solution system with high stability and high deposition rate.The simple copper plating bath was determined first. EDTP and EDTA·2Na double complexing agent electroless copper plating solution system was determined through the selection of four kinds of complexing agent of EDTP, EDTA·2Na, potassium sodium tartrate(Tart) and triethanolamine(TEA). The suitable molar ratio of EDTP, EDTA·2Na and Cu2+ was 0.8:0.6:1 determined by the control variable experimental method. The effects of main salt, reducing agent, and pH value on the deposition rate and stability of the copper plating bath were studied respectively by additional weight method and catalytic ink acceleration experiment method to finalize the simple copper plating bath composition was: 12 g/L CuSO4·5H2O, 10.7 g/L EDTA·2Na, 11.1 m L/L EDTP, 12 m L/L formaldehyde, and pH value was 12.5~13.0.The effects of additives on the deposition rate and stability of the plating solution were studied by weight gain and catalytic ink acceleration experiment method, the results showed that 2,2’-pyridine, potassium ferrocyanide, 2-Mercaptobenzothiazole(2-MBT) could effectively improve the performance of plating bath, and the suitable dosage was 10 mg/L, 20 mg/L, 1 mg/L respectively. A linear potential scanning method was used to research the function mechanism of additive in the plating bath, and the results showed that 2,2’-pyridine, potassium ferrocyanide, 2-MBT could decrease the deposition rate through hindering the oxidation of formaldehyde, thus stabilizing the plating solution system. In addition, potassium ferrocyanide could accelerate the start-plated, thiourea could accelerate the process of anodic reaction, but the excessive addition could lead the plating deposition rate to decrease sharply. The study on the additive compound showed that the deposition rate and stability of the compound additive was better than the single additive.The technological measures for improving the performance of the plating bath were studied in this paper, including the temperature, the load and the stirring speed. Eventually obtained a high deposition rate and stability plating bath(G-1), and the composition was: 12 g/L CuSO4·5H2O, 10.7 g/L EDTA·2Na, 11.1 mL/L EDTP, 10 mg/L 2,2’-pyridine, 20 mg/L potassium ferrocyanide, 1 mg/L 2-MBT, 12 m L/L formaldehyde, the bath temperature was 40~45?C, pH value was 12.5~13.0, load was 0~3.5 dm2/L, stirring speed was 600~1000 r/min. The electroless copper plating solution determined in this paper had comprehensive advantages in two aspects of deposition rate and stability, which could be applied to the industrial batch copper plating.