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A study has been carried out employing a vibratory motor, offering amplitudes of 0·4–4 mm at 50 Hz in acid copper sulphate as a model electrolyte in which α‐Al2O3 particles are suspended for co‐deposition, yielding a composite electrodeposit. Using a horizontal disc vibrator at the bottom of the container, perforated discs have been shown to give superior agitation and a laminar/turbulent transition has been identified. Incorporation of particles is a maximum at the transition. In the laminar regime Sh‐Re0·037 and in the turbulent regime Sh‐Re0·82. Mass transport enhancement was measured for a variety of disc and tank diameters and enhancement factors for electrodeposition of 3–40 times were obtained. In these circumstances a modified Reynolds number Re1 was employed Re1 = 100 ad2(d1−d2)/υd2 and, assuming a conventional dependence upon Sc, a full correlation of the type Sh1 = constant Re1a Sc0·33 was obtained where the constant took values of 10–40 and ‘a’ took values of 0·83–1·1 depending upon precise location within the tank of the mass transfer probe.

Introduction Much work has been done on the phenomenon of electropolishing since it was discovered by Jaquat. Most of this work was directed towards the elucidation of the polishing mechanism as well as establishing conditions for polishing of different metals and alloys. Studies on the polishing mechanism have revealed that electropolishing is a diffusion‐controlled process, which takes place at the limiting current, and electropolishing can therefore be treated quantitatively using the theory of mass transfer to the cathodic deposition of metal and metal powder. Some work has been done on the study of electropolishing under forced convection mass transfer conditions. A notable recent investigation involving copper and copper‐based alloys in a stirred cell is due to the study of Gabe and strongly suggests a diffusion‐limited mechanism at low temperature. Fouad et al. studied mass transfer under free convection in the electropolishing of vertical copper electrodes in phosphoric acid.

In the preface to his book, Dr. Gabe states that it is not a monograph but a compromise with several categories of reader in mind, thus setting himself a very difficult task. Basically the book appears to be aimed at the metal finishing aspects of courses leading to qualifications from the Institute of Corrosion Technology and the Institute of Metal Finishing.

Insoluble anodes have long been used as an alternative to the preferred soluble types, primarily for their practicality and without great attention to their efficacy. However, since about 1970 so‐called catalytic anodes, typified by platinised titanium, have been increasingly used for electrochemical processes without too much attention to possible side‐effects. The purpose of this paper is, therefore, to review the types of commercially available catalytic anodes and their electrochemical properties, particularly with respect to acid copper electroplating.

Commercially available catalytic anodes were obtained from various anode suppliers and their electrochemical properties and behaviour with respect to acid copper electroplating were studied.

While the oxidising capability of catalytic anodes is undisputed, it can lead to oxidation of organic species in electroplating solutions. This in turn can lead to loss of control and additional costs for additives in electrodeposition. This study has addressed the issue and the paper attempts to set down some data‐based rules for the selection process. It also discusses some ways of optimising the choice of anode for acid copper processing of printed circuit‐related processes.

The paper determines the benefits and problems associated with the utilization of catalytic anodes in acid copper electroplating baths and, in particular, their effect on brightener consumption. It describes the factors affecting this phenomenon and describes a novel method for overcoming it.

The 7th Annual Symposium of the Institute was held this year on Wednesday and Thursday, the 6th and 7th of May to avoid clashing with the Second Printed Circuit World Convention scheduled to be held in Munich during June.

Despite the fact that insoluble anodes are becoming more utilized in acid copper electroplating for printed circuit board manufacture, little work has been published on the impact of using such anodes on the process control of the baths or their effect on the electroplated deposit. In this study, two electroplating tanks were set up, which were identical in all aspects except that one tank used the traditional phosphorized soluble anodes, whilst the other employed insoluble anodes. Incorporating insoluble anodes into the electroplating tank caused a large increase in brightener consumption rate and the mechanical properties of the electroplate and the throwing power tended to be somewhat inferior to when soluble copper anodes were employed. This was thought to be due to the problems of controlling the brightener concentration at optimum levels rather than to any deterioration in the electrolyte, attributable to, for example, by‐product build‐up.

Significant reductions in the cycle time for the desmear, “making holes conductive” and imaging stages of the printed circuit board manufacturing process have been achieved by the use of horizontal conveyorised techniques. If these savings in time are to be fully realised, it is also necessary to have a high‐speed acid copper electroplating process that, by implication, must be capable of operating at very high current densities. This paper outlines the fundamental electrochemical principles of acid copper electroplating and explains how these impact on high speed electroplating in terms of the electrolyte chemistry, the construction of the plating cell and the method in which the current is delivered (i.e. DC or pulse).

The purpose of this paper is to develop and optimize anti‐corrosive multi‐layered coatings of zinc‐nickel alloy on carbon steel.

A variety of composition‐modulated multi‐layer alloy (CMMA) coatings of zinc‐nickel were developed on a carbon steel substrate by cyclic changes in cathode current during electrodeposition, coupled with variation of the thicknesses of the individual layers. The corrosion behavior of the coatings was studied in 5 percent NaCl solution by electrochemical methods. Cyclic cathode current densities (CCCDs) and the number of alloy layers were optimized for highest performance of the coatings against corrosion. The factors responsible for improved corrosion resistance were analyzed in terms of change in the intrinsic electrical properties of the capacitance value at the electrical double layer that was associated with micro/nanometric layering. The formation of the semi‐conductive surface film, which was responsible for the improved corrosion resistance, was supported by a Mott‐Schottky plot and the cyclic polarization study. The formation of multi‐layered deposit and the mechanism of corrosion degradation of the coating were analyzed using scanning electron microscopy.

CMMA coatings with an optimal configuration of (Zn‐Ni)_2.0/4.0/300 showed ∼35 times better corrosion resistance compared to a monolithic (Zn‐Ni)_3.0 alloy coating of the same thickness. The peak performance was attributed to the change in intrinsic electrical properties of the coating and this conclusion was supported by dielectric spectroscopy.

The paper describes the optimization of CCCD and the number of deposited layers by development of electrolytic deposition of anti‐corrosive multi‐layered zinc‐nickel coatings from a single plating technique.

Reports on the determination of rates of electropolishing of copper by measuring the limiting current of anodic dissolution of copper in phosphoric acid and in (water‐acetone) ‐phosphoric acid mixtures. Notes that the rate of electropolishing is decreased in (water‐acetone) ‐phosphoric acid mixtures and that the percentage inhibition of dissolution depends on the mole fraction of acetone, and its dielectric constant. Concludes with calculation of the thermodynamic parameters of activation.