Conductive Adhesives for Electronics Packaging

Citation

Ellis, B. (2000), "Conductive Adhesives for Electronics Packaging", Soldering & Surface Mount Technology, Vol. 12 No. 1. https://doi.org/10.1108/ssmt.2000.21912aae.002

Conductive Adhesives for Electronics Packaging

Conductive Adhesives for Electronics Packaging

Editor Johan LiuElectrochemical Publications Limited, IOMPages 431+xv; Tables 38; Figures 329; References 457ISBN 0 901 150 37 1Price US$158URL: http://www.elchempub.com/epfiles/ep35.htm.

Keywords: Publication, Adhesives, Electronic packaging

Wow! Now this is a book! I can say categorically that, until there is a radical technology change, this is the definitive work on electrically conductive adhesives. Before I get carried away by my enthusiasm, let me say that it is not perfect, even if it is pretty darn close to it. So, let's start by mentioning some of the weaknesses. Like all books written by several authors, it is very difficult for the editor to provide a seamless assembly. In this case, there are 18 chapters, written by 24 authors from three continents. There are therefore quite a number of repetitions and, dare I say it?, even a few cases where opinions may diverge. Many of the authors are not of English mother-tongue, but the quality of the edition is such that one would never guess it. However, my main complaints are probably nit-picking, but three-fold:

1. 1.

   an implicit assumption, in some places, that solder, and especially lead-containing solder, is already more or less obsolete. Whereas it would seem that European technocrats are determined to eliminate lead from solder in the next decade, the animal is not yet dead;

2. 2.

   in book reviews in the past, I have often complained that American authors were too parochial in their approach, often assuming that Europe does not exist. For once, not only are the rÂles reversed, but in trumps, particularly with respect to the chapter entitled Adhesives and health hazards, where the regulations quoted are the Swedish ones. Now, it is well-known that the Swedes are world leaders in health and environmental issues, but their regulations are not the same as most other countries. As just one example, on page 413, it is mentioned that methylene chloride has been banned in Sweden from the end of 1994 and trichloroethylene one year later. This may be useful information in Sweden but it is misleading in most other countries, where these two solvents are easily obtained with little or no restriction - especially developing nations, where they may be the only viable choice for some applications;

3. 3.

   there is very little practical advice on how to prepare a substrate for receiving an adhesive and how to apply the adhesive to it. Yes, there are little snippets of information dispersed through the text but no cohesive passages on these subjects, even though the reliability of an assembly can alter drastically according to the substrate properties, preparation and quality, as well as to how the assembly is made.

These minor criticisms apart, there is a wealth of information available about all the aspects of using the various types of conductive adhesives, and even non-conductive ones. Even the first chapter, an introduction to the subject, makes good reading for the initiated and the uninitiated alike, yet with a glance towards possible future technologies.

Each of the other chapters, too numerous to describe in detail, has been written by world-leader experts and, together, provide a marvellous insight into the mechanics, physics and chemistry of the subject. I must admit that the fourth chapter, in particular, fascinated me, describing the mathematical modelling of anisotropic adhesives and the calculation of the probability of opens and shorts. Another outstanding chapter is one which discusses the reliability of conductive adhesive joints in surface mount applications. In particular, there is a table summarising the reliability results of 11 different researchers: the shorthand necessary to put all this information on two facing pages is a little difficult, at first, but it is a typographical feat to transmit so many data in such a small space, without using a CD-ROM! A wee bit of a paradox, with respect to the title of the book, is a chapter on non-conductive adhesives for making electrical connections. This may become an attractive technique for some applications, especially where one member of the joint can be easily deformed to provide the co-planarity necessary for a good contact. I was relieved to find that there was also treatment of the thermal aspects of electrically conductive adhesives, especially with regard to die attachment. It would have been a mistake to have ignored this subject. Another chapter was devoted to the particular problems of conductive adhesive on glass, such as in displays.

Each chapter has many references. The indexing is excellent although a little frightening in some cases, because the same subject may be evoked in many different chapters. For example, the word "polymer" is indexed to no fewer than 50 places in the book (happily with a number of "polymer xxx" references as well, for a first subdivision of the indexing). Like Bartholomew's book, this one also unfortunately lacks an index of authors mentioned in the text and references.

In summary, I vote this work as the EPL "Book of the Year" - a very worthy addition to the already comprehensive collection of titles. The price is right, the contents are right, what more do you want? But one question remains: what readership does this book address? It is most certainly a must for the R&D department of any company even vaguely contemplating the use of electrically conductive adhesives. I would say it is also required reading for the more savvy production and process engineers who wish to understand the materials and processes they are using or wish to use. My guess, though, is that the technical and scientific standard of the book may be too high for the actual process operators to understand in some establishments. One thing I can guarantee: if you have this book on your library bookshelves, it will be well thumbed, very rapidly.

Brian EllisCyprus