SAFE: Introduction and Overview
January 5, 2011 | Joe Fjelstad, Verdant ElectronicsEstimated reading time: 7 minutes
Part 1: Introduction and OverviewIn August 2007, the concept of solderless assembly of electronic products was introduced to the electronics industry under the moniker of the Occam Process. It was so named to honor the 14th century English philosopher and logician, William of Occam, whose rigorous thinking and arguments favored and encouraged the finding the simplest possible solution to every problem. Occam indirectly inspired the idea of solderless assembly by way of his observation, often cited by logicians, that, “One should not increase, beyond what is necessary, the number of entities required to explain anything.” Occam’s words have been reinterpreted in more modern times as: “It is vanity to do with more than which can be done with less.” At the risk of providing a bit of excess background, it might be added that some readers' may be more familiar with the term “Occam’s Razor” which was adopted by scientists to test theories, noting that when one is presented with two or more competing explanations for a given phenomenon or observed effect, the simpler one is better and more likely to be correct. In the end, analysis simplification of electronic assembly by eliminating the solder process and all of its many processing and post processing steps seemed to pass the Occam litmus test and thus the name was chosen.
Occam Process proposes the use of less material and fewer process steps by eliminating solder from the electronics assembly process.
There was a great deal of initial fanfare surrounding the introduction of the concept and there was also a great deal of controversy, initiated with questioning whether such a technology would ever be viable. A number of comments were made pointing out that one component type or another was ill suited for such processing. These were true statements, but they were rooted in past and present views of the world. Such effort was not really necessary. Incumbent technologies are always hard to dislodge (inertia, both positive and negative is hard to overcome) and few incumbents ever really go away.
For example, while printed electronics are being hailed as the newest next “big thing” of the electronics industry, it is arguable that they have been in use for more than 60 years [1]. The term printed circuit was apparently chosen because the earliest circuits were, in fact, printed using a combination of conductive and resistive to make their products. Had there been an understanding of the transistor in 1946 and semiconducting inks available to them at the time no doubt the early printed circuit pioneers would have used them. It is worth noting that Jack Kilby worked for an early printed circuit manufacturer before joining Texas Instruments where he hand built the first integrated circuit using printed circuit materials (conductive ink and an insulating base). That aside, hybrid circuits were one of the products of the early printed circuit industry and membrane switches are another. Both products are still in use today 60 plus years later. More interesting is the fact that the recent visions and versions of printed electronics are actually solderless. Transistors and circuits are printed using organic insulating, conductive and semiconducting polymers and no solder. Semiconducting inks filled in the piece missing when the printed circuit industry was first born. Thus, solderless circuit technology is for all intents and puroses already underway in the world of printed electronic circuits.
Incumbent and other deeply rooted technologies persist for many years but still even they must be reinvented from time to time to keep pace with inevitable change.Turning back to the topic of electronic component types and, more specifically, IC packaging technology, there has been an explosion in the number of different types of devices available with numbers of different types now running into the tens of hundreds. One result is that entire businesses have been formed just to keep track of the component libraries. A few decades ago there were roughly 30 types of packages and most of those are still being used, especially the revered dual in line package or DIP which ushered in the era of the personal computer. Interestingly DIPs are still being produced in roughly the same numbers that they were a couple of decades back; however, they are a diminishing percentage of the total. Those making DIPs have nothing immediate to fear. DIPs are, by their very nature, a highly reliable package, they are just not of a form factor of interest to most designers and they cannot support the pin counts that are demanded of ever smaller and yet increasingly complex electronics.
Hundreds of IC package types are considered in design, representing all eras of electronic design--from through hole to SMT and from peripherally leaded to area array. Are they all necessary?Considering solder once again (either leaded or lead-free), let it be said from the beginning of this book on solderless electronics that solder will be used by most assemblers of electronic products well into the future, even though reliability experts often point out that solder joints have long been the weakest link in the electronic interconnection chain and a top cause for defects in manufacturing. The reason is quite simple. For more than half a century, the electronics assembly industry has been defined by the use of electronic solder technology to attach components to PCBs. But the industry has also been limited by the use of solder which has a number of restrictions associated with it. This includes the many different materials, processes and types of equipment associated with solder’s use. Solder assembly is a multi-billion dollar industry with roughly $1 billion dollars spent annually on solder alone. Moreover, despite its drawbacks, solder assembly has had a long and largely successful run. Even the EU’s lead-free mandate which caused the industry to spend tens of billions of dollars to make the conversion to lead-free solders has been endured (needlessly, from an environmental perspective, it turns out). Unfortunately, reliability experts point out that lead-free is causing electronic reliability to take a hit while energy consumption is increased and process windows are narrowed. Still, as our very human nature would have it, we accept the problems taking comfort in the old adage: “Better the devil you know.”
Lead-free solder has challenged the electronics industry’s ability to make reliable electronic products and has cost billions of dollars to implement. The value proposition of lead-free has been questioned repeatedly by both reliability and environmental experts.This book is a book about technology, but it is also a book about change or, at least, the promise of change. However, it is also a book that honors electronic interconnection technologies of the past and will seek to identify and explore developments which are already part of the knowledge base and important stepping stones in progress. It is hoped that by taking the reader through the history of solderless assembly, which is already quite established in many areas of electronic assembly, some of the trepidation associated with change will be lessened and a measure of comfort established with respect to the positive aspects that can only be attained by change. Change is not easy, but change can be managed. Preparing for change will require the adoption of new ways of thinking. Implementation of change and its management will require discipline. One must be rigorous in his analysis and resolute in his purpose if he is going to succeed in mastering change.Change is the only certainty in life, so might as well embrace it. It is easier to die than to adapt and change.In summary, solderless assembly for electronics is an over-arching concept for electronics manufacturing that is finding increased interest based on the number of different efforts that have been, or are being, undertaken to eliminate, or at least minimize, the use of solder in electronic products. The change is already underway as the industry faces the reality of the challenges of lead-free. While it has been suggested that, because of short product cycles, solder reliability is not important, those arguments ring hollow in a world where 70% of the world’s population cannot afford anything but the most reliable products because they cannot afford to replace them at the same rate as those at the top of the economic pyramid. Moreover, with knowledge expanding at an exponential rate, we must test our assumptions much more often than we have in the past. We must ask ourselves questions to guide our decisions. With that thought in mind, let this opening part of the series end with a simple question: If the reader had a prior knowledge of everything they presently know about the electronics manufacturing industry, including, design, manufacturing and testing, and also had the ability to build the electronics industry from the ground up, would one choose to do things exactly as they are being done today?
Short product cycles are not a legitimate excuse to make less reliable electronic products when many of the world’s neediest people cannot afford to replace their electronic products at the same rate as those in the developed world.
A request to readers: If as you read through this new serialized book, you find discrepancies, errors or have thoughts for inclusion in this work in progress or any questions, please forward them to me here.
Verdant Electronics
References:1. Brunetti, Cledo and Curtis, Roger W., "Printed Circuit Techniques," National Bureau of Standards Circular 468, November 15, 1947.