Plating characteristics

At Coventry University [20] we have obtained similar results to Tu under conventional (silent) conditions. Our initial thoughts were that if the effect of the tail off was either a consequence of mass transfer to the electrode, or a consequence of some problem with the diffusion layer, then ultrasound might be expected to have an effect and thus improve the plating rate. Investigations in the presence of ultrasound and at various pH values did not significantly affect the plating characteristics i. e. the plateau effect still remained. However, the overall efficiency in the presence of ultrasound was affected (Fig. 6.10). 

It was suggested previously that one of the obvious variables to change in order to provide for increased plating rates was the current density. The more current applied (in a given time), the faster the coating should develop. Fig. 6.12 compares the effects of increasing the current density (CD) on the plating characteristics for Cr(VI) and Cr(III) [21]. Only for Cr(VI) is the effect as predicted. 

Optical Properties. The addition of lanthanum oxide to PZT has a rather remarkable effect on the optical transparency, especially when the amount of lanthanum exceeds seven atom percent. Thin polished plates characteristically transmit about 67% of the incident light. When broadband antireflection coatings are applied to the major surfaces, this transmission is increased to greater than 98%. Surface reflection losses are a function of the index of refraction (n = 2.5) of the PLZT. 

The quantity fco is the permeance (as defined in the diode discussion) of the triode, and its value is specific to a particular triode type. The plate characteristic curves generated by Eq. (5.4), for a triode in which fco = 0.0012, are illustrated in Fig. 5.8. As the plate characteristic curves indicate, the triode is approximately a voltage-controUed voltage source. 

FIGURE 5.9 Tetrode plate characteristic forasinglegrid voltage (at constant screen voltage). 

To suppress the negative-resistance characteristic generated by the tetrode, a third coarse grid structure (the suppressor grid) is inserted between the screen grid and the plate. In this manner, the plate characteristic curves are smoothed and take the form shown in Fig. 5.10. 

FIGURE 5.12 Triode plate characteristics with superimposed DC load line for Q-point calculations. 

As is illustrated in Fig. 5.15, a DC load line is applied to the pentode plate characteristics in the same manner as for the triode. In the example shown, Rl = 1 and the Q-point values are Vp = 300 V, Ip = 200 mA, Vg —9 V. Note for this device that positive-grid operation is possible and that nonhnearities occur for large negative grid voltage because the curves are not evenly spaced. An AC load is added to the pentode plate characteristics in the same manner as for the triode case, and the graphical analysis proceeds in the same manner as for the triode. 

Examples of such expressions for selected cases used in VLSI packaging conditions are presented next. Convection heat transfer coefficients he averaged over the plate characteristic length are written in terms of correlations of an average value of Nu vs. Ra, Re, and Pr. 

Fig. 3.1 Curve 1 absolute intensity (except for an arbitrary constant) of the phosphorescent emission of crystal violet in glycerol at 178 K, showing the alpha and beta bands. Curve 2 similar absolute intensity of fluorescent emission (plus 5-10 % phosphorescence), at 178 K. Curve 3 for reference, the absorption spectrum. Curve 4 intensity of green phosphorescence band (not corrected for plate characteristics). Reprinted with permission from [3]. Copyright 1942, American Chemical Society...

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