Customer Reviews

Implementing Lead-Free Electronics (Professional Engineering)

5 star:		(1)
4 star:		(0)
3 star:		(1)
2 star:		(0)
1 star:		(0)

 

 

As one with a background in electronic materials and device reliability, including solder fatigue, I found this book to be basic and lacking rigor. It's essentially a hodgepodge of sundry facts and studies concerning surface-mount practices, with similar facts grouped into various chapters on different soldering techniques, the available Pb-free alloys, coatings for PCBs and components, and reliability. The shortcoming with this approach, as I see it, is that Ms. Hwang tends to toss out lots of facts and let the reader draw his own conclusions. In those places where she does offer definitive conclusions, she follows the party line while offering little else. I'd expect an author of such a book to not only discuss the state of knowledge but also synthesize that knowledge into firm guidelines that can be extrapolated to any manufacturing scenario, not just the specific ones cited. This book lacks that, which I see as its primary weakness. For example, one sometimes gets faced with a bewildering array of facts (for example, solder x exhibited a wetting force of 10 at temperature a whereas solder y exhibited a wetting force of 20 at temperature b, but solder z exhibits a wetting force of 30 at temperature c) and left to consider the implications for, say, solder w. Many times Ms. Hwang summarizes the conclusions, but not always. As another example, the chapter on accelerated cycling merely stated typical temperature extremes and cycle quantities but never mentioned how those accelerated tests correlated to real diurnal cycling (as through, for instance, the Coffin-Manson or Engelmaier formulations). Thus, I don't see how anyone could use that information to design an intelligent accelerated reliability test. The result is that the book didn't always give me that full, satisfying feeling of a well-planned guide.

On the positive side, this book contains numerous case studies that illustrate manufacturing practice. There is also decent background given on the basics of relevant technologies such as solder paste and reflow soldering. There are useful data to be found in this book, surely. Overall, though, it's not THE definitive guide, notwithstanding the blurb on the book's back cover. Perhaps this is because Dr. Hwang didn't intend for this book to be an in-depth examination of manufacturing practice and theory or maybe because the state of knowledge of Pb-free practices isn't that advanced. Even then, in my opinion the book could have been more thorough and seamless. For that, I highly recommend _Handbook of Lead-Free Solder Technology for Microelectronic Assemblies_, edited by Puttlitz and Stalter and published in 2004 by Marcel Dekker.

Dr. Jennie Hwang's second major book on lead-free electronics plays the ministerial role to its magisterial predecessor. It is the facilitator, carrying us from the calm of the laboratory to the clamor of the factory floor, where theories and realities collide. In the lead-free as in other worlds, implementation, not theory, ultimately determines survival.

The book follows the flow of factory implementation, moving from selecting the best approach, to choosing proper materials, to controlling the soldering operation, to concerns about compatibility, costs, and reliability. The prelude is a reality check of present manufacturing practices. Here Dr. Hwang shows us how the actual conditions of use for today's eutectic lead-tin solders, rather than theoretical arguments, justify the "drop-in" approach to lead-free replacements.

The key to manufacturing implementation is recognizing the interdependence of process decisions, to insure compatibility at every stage. Solder selection summarizes some of the voluminous technical detail of Dr. Hwang's prior book, supplemented with side-by-side solder comparisons.

Mass reflow soldering and wave soldering comprise separate chapters, again starting from a solid base of "real-world production demands." For mass reflow soldering, these include the difficulty of monitoring and controlling temperatures in a fast-moving environment. Wave soldering is dismembered in detail. New hobgoblins here are dross, corrosion, turbulence, and compositional stability. Again, case studies tie the text to factory-based data.

The open, bullet-point format of much of the material will make this a handy reference book, as well as a worthy supplement to its predecessor. Dr. Hwang has enlisted her long industry experience, her understanding of solder manufacturing, and her sensitivity to the concerns of students in her lead-free training courses to present an exhaustive, normative, two-volume approach to lead-free technology and implementation.