The Occam Files No. 3

The Occam Files No. 3

A Brief History and Critique of Solder in Electronics

 Solder has been used as a metallurgical joining technology for many centuries. The ancients discovered that it was possible to join different metals to create tools, weapons and art by using a mixture of tin and other metals, most commonly lead, which melted at a relatively low temperature, making it unnecessary to melt the joined elements of a construction. That solder found application in the construction of printed circuit based electronic assemblies seemed predestined. Tin-lead solder alloys of 60Sn/40Pb and 63Sn/37Pb became the work horses of the electronics assembly industry and remained so for decades. However in the late 1990s, alarms were sounded about the dangers of lead, based not on evidence of risk of evidence of harm to electronic product users but on historical uses of lead in paint and gasoline which were true vectors for lead getting into humans and the environment. (by today’s new lower standards nearly everyone who lived in a city with routine traffic congestion in the 1960s and 1970s had blood plasma lead levels that exceed current limits) Moreover, the more curious and questioning among industry interconnection technologists in the electronics industry determined that the amount of lead in electronic solder at the time of the ban represented roughly 0.5% of all the lead used globally and sadly, before science had a chance scientifically show that there was little to no risk of individuals being harmed by lead in electronic solder, the EU parliament, lobbied (evidently) heavily by the tin industry, took it upon itself to ban lead from electronic solder. (Note: for the purposes of full disclosure, it is important to note that some people in the world have been harmed by lead in electronic solder. These were the unfortunately poor, uneducated and unskilled individuals in China and South Asia who were given the opportunity to make a living by disassembling electronics waste containing lead alloy solders from the developed world. Those poor individuals were however given no instruction, no proper tools and no protective gear. It was a callous and selfish dumping of a problem on to the poor and unsuspecting for ill-gotten profits and it is deeply regrettable that the process was to heartlessly and badly managed. (It was not, however, because tin lead solder is inherently harmful in a static condition)

As a huge part of the electronics global market, the rest of the world was compelled to follow their lead. The EU was assured by lobbyists that lead-free solder alloy solutions existed and that the transition would not be difficult or expensive. Unfortunately, nothing could have been further from the truth. The truth is that the transition was neither easy nor inexpensive. It has been estimated that the transition cost the electronics industry well over $100 billion in research and development of new materials for PCBs to withstand the higher temperatures of lead-free solders, new alloys to address the unfulfilled promises of the “drop in” replacements, new equipment to deal with the corrosive nature of high tin solders and many other issues coupled with the need to purchase previously unnecessary compliance assurance tools such as XRF (X-ray fluorescence) tools to detect the presence of lead. The total cost of lead-free conversion continues to mount year by year. It also unleashed a substantial number of new problems that affected both the quality and reliability of electronic products. After the introduction of lead-free, a host of new conditions and terms to describe them entered the industry lexicon: graping, champagne voids, pad cratering, Td (temperature of decomposition) and others and the industry experts had to develop new methods to detect them and new materials and processes to try and ameliorate them. It has not been inexpensive nor entirely successful.   The readers of this article are invited to look at any electronics industry technology magazine or journal and check out for themselves the percentage of content related to meeting the challenges of lead-free solder. New alloys, new solder pastes, new approaches to solder paste deposition, new “optimal” land patterns,  new failure mechanisms, new cleaning methods, equipment and chemistry, new test methods, new solder joint quality detection tools, etc., the list could go on but better, the readers assess this for themselves. The deluge has been robbing us of our vision. We cannot see the solutions are a big, if not the biggest, part of the problem. We as an industry are continuing to, in Sisyphean fashion, push the boulder up the hill day after day only to have it roll back down the hill every night. It is a needless yet ongoing expense that burdens the global electronics manufacturing industry to the tune of many tens of billions of dollars annually.

In the run up to the ban, there was a relatively small contingent of scientists and engineers, who like the boy in the fable “The Emperor’s New Clothes” called out the nakedness of the lead-free effort but the truth is that it was determined that there was more money to be made by going along with the change as was just alluded to rather than fighting it. For my continued vociferous opposition to the lead-free mandate and appeal to look at the science before making the leap to change, I was personally (but good naturedly I’m sure) caricatured as Don Quixote. Still to this day, because science and truth were my guiding lights, I have never apologized for my opposition to lead-free as a "environmentally beneficial solution".

Interestingly, I now feel I owe the ill-conceived lead-free movement a debt of gratitude because it was the ban of lead in solder that they sought that caused me to realize that a better solution for making cheaper, better, smaller, more reliable and more environmentally responsible electronics was to make them without solder. Lead-free was the impetus and progenitor of the Occam Process and what has come also to be called Solderless Assembly For Electronics or SAFE Technology for short.  

In closing, the reader is invited, once again, to read the headlines or titles of stories from any electronics newsletter, magazine or journal with a manufacturing focus and see and consider for themselves the risks and benefits of solder.

Finally, for those whose careers are tied to the solder industry (which includes many dear friends whom I have known for many years) I say this: “Do not fear the concepts being proposed here” The reality is that there is a huge inertia in the electronics industry. Change is a scary thing but it is constant, even though it may take a long time. Mountains are washed to the sea slowly. I personally take heart in the words of Victor Hugo who wrote: “Nothing is more powerful than an idea whose time has come”

But first the idea must be made known.

Next time: Building Electronic Assemblies in Reverse.