Book Reviews

Lead-Free Electronic Solders
A Special Issue of the Journal of Materials Science: Materials in Electronics
By K.N. Subramanian, Editor

This 375-page text is more a collection of papers than a book, but its specific focus is on lead-free material science and is ideal for engineers. It is for the person who wants to go past the alloy types and understand the elements and their interactions during the assembly process and potential joint reliability.

All papers were produced for a special issue of the Journal of Materials Science, Materials in Electronics. The publisher felt this would make a valued contribution to the wider marketplace, and I agree. There is a fair amount of duplication in the text on the whys of lead-free, but this does not detract from the final compilation. The main part of the text is devoted to soldering materials, with all the most common alloys illustrated and supported with mechanical data and phase diagrams.

Researchers from the chemical engineering department of Tsing Hua University outline most of the common alloy data gathered from a wide source of papers and reports. They compare the information and highlight differences in the available data. Where possible, they suggest where more investigations are necessary for a better understanding of each material set.

Laura Turbini provides a chapter on soldering materials and their possible impact on corrosion at elevated temperatures. Because of her long interest and research work into Conductive Anodic Filament CAF formation, this is covered with good examples of the way in which this form of electrical short can occur. It has been demonstrated in many studies that, where greater stress is put on laminate, it is possible for separation of the glass and epoxy bundles to open up a path for CAF formation. However, some simple design rules often are not used to increase product reliability.

A paper by Darrel Frear of Freescale outlines well the issues facing consumer electronics, and the most common or potential failure modes. The text is well illustrated with examples of typical joints and solder interface structures. Care is taken to discuss one of the most challenging tests with lead-free alloy drop testing. A draft standard from the IPC/JEDEC is available as a second source of information.

Other chapters consider tin whiskers, tin pest, electromigration in lead-free solder joints, and the impact of RoHS on high-performance electronics. The paper on high-performance products is split into two sections and authored by Karl Puttlitz and George Galyon. It covers other interconnection methods that may be impacted by RoHS. Karl, originally with IBM, is now working as a consultant after his retirement; he co-edited other excellent books on lead-free and BGA when he was still at IBM.

This is not a holiday read for most people, but there is a lot of value in the information to research and process engineers who want to go deeper into the subject.

In the publishing industry there are many charts and awards for the best selling books, but with sales in the tens and hundreds—not thousands—it would be impossible to have a sales chart for technology handbooks. So, here is a list of "Bob Willis' Top Ten" reference books that has been updated to take into account recent changes in technology.

This list does not indicate the number of sales of any one title, the age or up-to-date nature of the text, only my opinion on the "must have" engineering titles for your office bookshelf. Remember: Generally no new problems in manufacture exist; most have been seen before by someone.

This list does not indicate the number of sales of any one title, the age or up-to-date nature of the text, only my opinion on the "must have" engineering titles for your office bookshelf. Remember: Generally no new problems in manufacture exist; most have been seen before by someone.

Good reading until next time.

  • Printed Circuit Handbook (5th Edition)
    Clyde Coombs, Jr.
    McGraw Hill

  • Electronic Failure Analysis Handbook
    Perry L. Martin
    Mc Graw Hill

  • Microelectronics Packaging Handbook (1st Edition)
    Tummala and Rymaszewski
    Van Nostrand Reinhold

  • Comprehensive Guide to Design, Manufacture of Printed Board Assemblies
    Bill MacLeod Ross
    Electrochemical Publications

  • Quality Assessment of Printed Circuit Boards (Out of print)
    Preben Lund
    Bishop Graphics Inc.

  • Reflow Soldering Processes and Troubleshooting
    Ning Cheng Lee

  • SMT for PC Board Design (2nd Edition)
    James Hollomon
    Prompt Publications

  • Soldering in Electronics (2nd Edition)
    Klein Wassink
    Electrochemical Publications

  • Ball Grid Array Technology
    John Lau
    McGraw Hill

  • Flexible Circuit
    Joe Fjelstad
    Electrochemical Publications

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ImageEdited by Sanka Ganesan & Michael Pecht
Published by CALCE EPSC Press
Paperback with 11 Chapters, 450 pages with diagrams and photographs.
ISBN 09707174 7 4

This book came to my attention through a direct mailshot from CALCE. I have been on their circulation list for some time; this group are involved in very diverse projects. I feel that this text may not get the coverage it deserves, I will try to ensure as many people find out about this book as possible, as it is good value.

One chapter is part written by Jasbir Bath who I know from his days at ITRI in the UK, now Soldertech/Tin Technology. Jasbir and his colleagues at Solectron provide an overview of the practical production issues of lead-free manufacturing including their personal experiences. Solectron have also supported this reviewer in the UK, they are one of the leading contractors in lead-free. Jasbir covers each step in the process including, printing, placement, reflow, wave rework and inspection. The chapter tries to pick up the practical issues of controlling material and products in a demanding contract market with the different demands of customers all trying to come to grips with lead-free.

The book contains chapters mainly written by staff at CALCE but with contributions by industry and one other University balancing theory with practical work. The foreword is by David Bergman, IPC's Mr Lead-Free who outlines industry position and the need for industry co-operation. Further chapters cover alloys, components, assembly and, of course, reliability. I thought the text on components was very useful covering some of the failure modes and methods of test. I also like the section on lead plating and the problems associated with plating chemistry.

A number of chapters references the SMART Group based on their Mission to Japan Report and the Mission to Japan seminars we ran after our visit. SMART Group, however, cannot take credit for bringing this directly to the author's attention as the editorial references are all from Tim Fryer's coverage in EM&T, Tim is editor in the UK, well done Timbo!

I particularly enjoyed reading the chapter on the cost of lead-free introduction, a simple tick sheet for engineers would have been valuable as well. Most of the areas of cost were highlighted with some exceptions. Like most engineers the author likes to see inside products so the final chapter on lead-free applications was interesting. Looking at the product build just a like a strip down investigation. I felt with the number of products in the marketplace this should have been greatly expanded.

I felt that all the key topics were well covered and any engineer would benefit from reading this book on lead-free. It covers many of the key points and is up-to-date with some good references. A very useful reference source and at an affordable price. With the dollar price approaching $2 to £1 pound, like Levi jeans it's a great time to buy!

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ImageEdited by Katsuaki Suganuma
11 chapters, 342 pages with photographs, tables and diagrams
ISBN 08247 4102 1

Here is another multi author textbook to hit the streets on lead-free, surely more will follow in the coming months as we move closer to July 2006. Katsuaki is the author of other titles like Lead-Free Handbook and I believe a Hand Soldering Guide which has only been circulated in Japan, hence Japanese only. He is based in Osaka University and I had the pleasure of meeting him in Japan with the SMART Group Mission. He was also the engineer to do some of the first work on fillet lifting on through hole lead-free joints. I have featured his first text book in past review pages, a limited review as the text was in Japanese, now as promised is this new book.

Authors contributing to the book include Kay Nimmo, Bill Plumbridge, Carol Handwerker, Tetsuro Nishimura and Masao Hirano amongst others. There is a nice section on tin whiskers which I found very interesting, like most people the subject has been done to death so it's good to see a different approach. Yun Zhang covers the topic in relatively simple terms and describes a variety of process experiments. His final conclusions are there are still many unknowns, a solution can work for one application but end up not working for others. It was also interesting the coverage given to the application of whiskers on demand.

Carol Handwerker from NIST covers material science; our own Kay Nimmo and Bill Plumbridge cover alloy selection and material performance. All of which are fundamental in understanding and comparing what we know about tin/lead solders and what we don't about lead-free. Each will have spent many hours producing the material and researching different data sets that exist.

One chapter is written by Shinichi Fujiuchi who represents one of the larger contract manufacturers in the world, Sanmina - SCI. Shinichi outlines the reflow assembly process including solder paste performance. An interesting topic that this reviewer was not aware was the reason that solder paste with zinc print wonderfully well for a short period of time then turn to a block of concrete. Apparently the zinc reaction products degrade the flux and other elements in the vehicle increasing the viscosity. One supplier has been investigating a coating process to reduce this effect, another application for OSP coatings?

Shinichi also covers a new solderability test procedure for components using solder paste in conjunction with a wetting balance. The technique is used to more closely mimic the process used in production. It will be interesting to see if solderability test equipment suppliers like Concoat look at this test procedure in the future as an option to the solder globule. It was a little disappointing that the reflow process was not covered in much detail with most attention paid to the materials.

The book again guides the user to the inevitable choice of tin/silver/copper as the lead-free alternative but with the use of tin/copper family for wave soldering and manual assembly based on cost. I guess my criticism with the book is the translation in a couple of chapters, which makes it difficult to follow the flow, but still worthy of review.

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ImageEdited by Richard Ulrich and Leonard Schaper
14 chapters, 370 pages

I met Richard Ulrich for the first time this year and he is very enthusiastic about the use of embedded technology I enjoyed the last part of his workshop at APEX. We hope to have him present a workshop in the UK with NPL in the near future. I believe this is the first text book to cover this development in PCB technology, no doubt there will be more like the conferences and other infrastructure that is growing up to support it.

A strong point that Richard and his co-editor state is that this is still an evolving technology and it will continue to do so over the next few years. Richard is firmly of the opinion that resistor technology and the use of conductive inks will be the first process to be actively used. This is covered in his live "Engineering Spotlight" interview feature for the SMART Group web site

The book covers each of the technology options, conductive polymers, capacitor techniques, integrated inductors, electrical performance, design and economics. There are guidelines on some of the design issues with fundamental information on capabilities and the PCB fabrication requirements. The chapter on the economics does give two case studies comparing conventional technology and the use of embedded resistors. A second case study is based around one of the NEMI projects.

A key point raised is the need for design tools and simulators. Inevitably these will come but there has to be a demand for time spent to develop tools for this technology. The basic material and their capabilities are known but not what happens during the fabrication and assembly stages. This comes from manufacturing experience in manufacture or funded research projects; it's that cart and horse thing again.

Sorry to Richard for scribbling notes over his book but thanks for autographing it; when he is rich and famous I may be able to sell the book to a fan.

Interactive Guide to Flexible Circuit Technology
Produced by Teknoflex

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