Copper-plating baths

Copper-plating bath compositions of various types have been used. A typical bath formulation consists of 200 g copper sulfate crystals, 30 mL cone, sulfuric acid, 2 mL phenylsulfonic acid, and 1000 mL distUled water. A pure copper anode may be used a copper anode containing a trace of phosphoms reduces sludge accumulation in the plating bath. 

Acid Copper. Bath compositions are shown in Table 8. The acid sulfate bath is by far the most widely used copper plating bath, both for plating and for electroforming and electrowinning. The fiuoborate baths have been Htde used in spite of the high current densities possible. Additional information can be found in the Hterature (98,99). 

Price [67] has reviewed the application of atomic absorption to a variety of plating solutions. Iron, lead and zinc are reported as the main impurities in cyanide copper-plating baths which may contain up to 200gl 1 of copper sulphate a twenty-fold dilution of the sample for trace determination is recommended. Nickel baths may contain 60 gl 1 of nickel and it may be necessary to monitor copper, zinc, iron, lead, chromium, calcium and magnesium at the ppm level. The standard addition method is probably best for such an application. Zinc has been extracted with trioctylamine-hydrochloride when present in the range 0.03—10pgml-1 in a nickel plating solution [68]. The zinc was re-extracted back into 1M nitric acid for... 

Fig. 14. Coulostatic potential decay curve for a copper electrode in an electroless copper plating bath (M. Suzuki et al., 1982 [22]).

A typical electroless copper plating bath contains divalent copper, EDTA as a com-plexing agent, NaOH, formaldehyde as a reducing agent, and (a) small amount(s) of additive(s) to stabilize the bath and to impart desired physical properties to the deposit. For thin metallization purposes, the bath may remain at room temperature, but the full-build bath is operated at elevated temperature. The composition and operation conditions of a typical full-build bath are shown in Table 11 [124]. It is well known that the two partial reactions are [3, 4] ... 

Fig. 23. Rate of copper deposition, determined with a quartz crystal microbalance, vs. potential in an electroless copper plating bath at various formaldehyde concentrations. A 0 mmol dm HCHO, 15 mmol dm , 30 mmol dm , 45 mmol dm", O 60 mmol dm (B. J. Feldmann et al., 1989 [131]).

Fig. 4 Influence of time of anodic galvanostatic treatment of a 2 M H2SO4 copper plating bath solution containing approximately 2000 ppm of organics (see text). Note that 10 h of charging corresponds to the passage of 180000 C L 1 of...

Use For preparing and maintaining cyanide copper plating baths based on potassium cyanide. 

Figure 8.9 Regeneration of chemical copper plating bath by electrodialysis.

Recently, at my place of work, I had occasion to order one pound of Rochelle salts (potassium sodium tartarate) from a major chemical supplier. This material was for use in a laboratory scale cyanide copper plating bath, where the Rochelle salt acts as a complexor. To get them to sell me this material, I had to answer a battery of questions, in spite of the fact that the firm at which I work has had a long customer relationship with this major chemical supplier. Less scrutiny of tartaric acid purchases would likely be encountered from a firm which supplies chemicals to the plating industry. To get tartaric acid from Rochelle salts, just dissolve them in water, and then add hydrochloric acid until the pH of the decimolar solution reaches 2. 

Corrosion Protection by Metallic Coatings 577 Tab. 4 Composition and working conditions of different copper plating baths... 

Uses Copper plating baths for printed circuit boards... 

The prepared microcapsules were added into normal nickel-plating or copper-plating baths to determine how they would co-deposit with the metal ions, the effects of different types of metal ion, and the process parameters required for co-deposition. 

Properties of the Copper-Plating Bath Containing Microcapsules... 

Microcapsules prepared with silicone resin or lube oil as the core and PVA as the wall were incorporated into the copper-plating bath (for composition, see Table 9.2), and electrolytic co-deposition was carried out at current densities (D(J of 10,... 

In the composite nickel-plating bath, conductivity clearly exceeded that of the composite copper-plating bath, but decreased much more rapidly compared to that of the copper-plating bath. The higher conductivity of the organosihcone-micro-capsules makes them easier to co-deposit. Clearly, the nature of the wall material also has a remarkable effect on conductivity. 

The incorporation of microcapsules changes the adsorption potential range and decreases the differential capacitance of the copper-plating bath. Figure 9.13 also shows that the incorporation of microcapsules into the nickel-plating bath induces a wide adsorption potential range and a small differential capacitance value. Such adsorption is also helpful for the co-deposition of the microcapsules with Ni + in the bath. 

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