A Techie Book Review: Pulse Plating

Estimated reading time: 5 minutes

A book review from Professor Martin Goosey, IeMRC Industrial Director.Pulse PlatingBy: Wolfgang Hansal and Sudipta RoyEugen G. Leuze Verlag KG D-88348 Bad Saulgau, GermanyISBN: 978-3-87480-265-9Published: 2012

Although electroplating has been in industrial use since the 19th century, the technique known as pulse plating is a more recent development. Interest in pulse plating began during the 1970s and, since then, a huge amount of work has been reported, both on the fundamental science and in terms of bringing the technology to commercial application through use in industrial production. Following the initial fundamental work carried out approximately 35 years ago, the development of new and increasingly sophisticated electronically-controlled rectifiers, along with computer-aided process simulation techniques, has enabled pulse plating to become a valuable production tool in numerous high-technology applications including PCB fabrication. Although there have been many papers and several earlier books published on the subject, this new work by Wolfgang Hansal and Sudipta Roy provides a more up to date compilation of the basic science coupled with details of the latest developments, possibilities, and applications associated with this powerful technology.

The main body of this substantial work is prefaced by forewords from three well known experts in the field. The first, "Pulse Plating in the Third Millennium," is by Peter Farr who gives a review of a sample of relevant papers published in recent years on pulse plating. The second, “Past and Future of Pulse Plating: An Introduction,” is provided by Wolfgang Paatsch, an expert active in this field for a great many years. The final foreword is by Sudipta Roy and Wolfgang Hansal,who have not only edited this major work, but also contributed to each chapter, either individually or in collaboration with four other authors.  

Following these useful introductions, the book moves on to a series of individual chapters covering all aspects of pulse plating, from the fundamentals to the equipment and processes for the deposition of a range of metals. Conveniently, the book is arranged in four sections that start with the fundamentals and then move through implementation to applications and, finally, special systems. The first section on fundamentals comprises seven chapters beginning with an overview of pulse deposition and then taking in chapters on thermodynamics, reaction kinetics, nucleation and morphology, current distribution, mass transfer, and modelling of pulse plating. This section thus provides a detailed review of all of the underlying scientific aspects that need to be understood by anyone working in this area who desires to gain a deeper knowledge of the subject.

The second section on implementation then covers the key aspects that will be of importance to those engaged in the actual utilisation of pulse plating and its three chapters cover pulse rectifier systems and the technical implementation of pulse plating processes, along with energy and material considerations. Rectifier designs and their associated performance capabilities have advanced significantly in recent years, giving much more versatility in terms of pulse waveforms, duty cycles and a number of other key factors and these are all covered in some detail in this section.

The third section on applications has six chapters detailing the use of pulse plating to deposit a range of important metals and alloys. The section begins with a chapter on the pulse plating of copper in printed circuit board fabrication. Interestingly, this was the first significant commercial application for pulse plating and it continues to provide a valuable approach for the deposition of copper in complex circuit boards. In particular, it enables the plating of high aspect ratio holes and vias that could not successfully be deposited using traditional conventional electroplating techniques.This chapter will be one that is of particular interest to those involved in the manufacture of PCBs and it offers a broad coverage of the key subject matter that will be of interest to such readers. The chapter covers not only the historical development of pulse plating techniques for use in printed circuit fabrication, but also the reactions that take place and which influence the overall efficiency. The demands on copper deposited in PCBs are broad and challenging and are their attainment is fundamental to the performance of all of the modern electronic goods upon which society increasingly relies. As boards increase in complexity and interconnect density, a key demand is for enhanced throwing power and this subject is also covered in detail, from the basics of current distribution and Wagner numbers to surface distribution, plating of through holes, and blind vias. The copper deposits used in PCB interconnects require a very specific set of properties and associated structures and morphologies and the chapter covers these aspects before concluding with a brief introduction to the more complex approach of superimposed pulse reverse plating and some information on recommended pulse plating parameters and settings. The following five chapters cover nickel and its alloys, tin and its alloys, chromium, precious metals ,and zinc and its alloys. The chapter on the pulse plating of precious metals includes gold, silver, palladium, platinum, rhodium, and various alloys.

The final section of the book is on special systems and its three final chapters discuss pulse polishing, machining, and anodising, the deposition of nano-structured metal multilayers and pulse plating in combination with particle dispersion.

With a total of three forwards, 19 chapters, a list of over 800 references, and a very extensive index, this work of almost 400 pages provides a comprehensive compilation of all of the important subject matter that comes under the umbrella of pulse plating. Rather unusually for a book of this type, the final pages following the index are dedicated to advertisements from a number of organisations active in the field of pulse plating and who will doubtless be good sources of further information for readers interested in implementing the technology. The book covers the basic science, the equipment needed, and the use of pulse plating to deposit a wide range of metals and alloys. For those with an interest in electrodeposition, this book contains a wealth of information and it provides an excellent work with which to learn more about this extremely interesting and relatively new electroplating technique. The authors are to be congratulated for preparing such a valuable and important new work that will be of use to both academics and industrialists.