Throwing power discussion

We distinguish between macro throwing power and micro throwing power. We discuss the former first. This quantity is often measured using the Haring—Blum throwing power box (see Fig. 12.2). The throwing power is then expressed by... 

Having defined the throwing power quantitatively, we can now proceed to discuss the physical reasons for the dependence of the throwing power on geometry and the methods available to increase the value of the T.P. to acceptable levels. This discussion refers to the so-called macro throwing power. In Section 30.3 we shall discuss the micro throwing power, which controls the smoothness of the deposit and depends on quite different factors. 

This leads us to the discussion of the methods by which the throwing power can be increased. Increasing the conductivity of the solution is an obvious approach, but is limited in scope. A specific resistivity of 5 ii cm, found it the case of the so-called acid copper bath, which contains CuSO and H SO, is about as low as one can get in aqueous solutions. The other approach is to decrease i. The kinetics of metal deposition from tlie simple ions is usually fast, but when the ion is complexed, much lower values of the exchange current density can be realized. This is one of the reasons for using cyanide baths for the electrodeposition of many metals. Copper, for example, can be deposited from an alkaline bath containing KCN. Instead of the usual aquo-complex [Cu(H O) ] one has the much more stable (K = 5.6x10 ) cyanide... 

It is to be noted that almost all the metals and/or alloys that can be electrodeposited from aqueous solutions can also be electro-lessly deposited under proper conditions. Due to simplicity, excellent throwing power, uniform deposits, and ability to coat various complex shapes, electroless deposition was intensively investigated for many industrial applications. In this section, recent developments in the field of electroless deposition are discussed. Considering very different applications of electroless deposition, the discussion is presented as follows ... 

Discuss the sequential reactions or processes in thermally activated (conventional) CVD of a ceramic compound. Which reaction conditions are preferred for determination of kinetics intended to study surface reaction kinetics Which process conditions are required for the production of fine powders Which conditions are necessary for good throwing power (uniform step coverage) ... 

This leads us to discussion of the methods by which the throwing power can be increased. The most common method is to use suitable additives, as discussed in Section 19.3.3. Indeed almost all industrial plating baths contain additives of one kind or another, used to improve the uniformity of coating, as leveling and brightening agents and to relieve internal stress in the deposit. 

Having defined the throwing power quantitatively, we can now proceed to discuss the physical reasons for the dependence of the throwing power on geometry and the methods available to increase the value of the TP to acceptable levels. 

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