Department of Materials Science and Engineering

Sometimes the culmination of painstaking research comes into a world that is just waiting for a change. Sometimes the world needs to do a little changing first.

The lead-free solder alloy developed by Iver Anderson, an MSE adjunct professor and Ames Laboratory senior metallurgist, is becoming an industry standard in a world that is increasingly more sensitive to technology’s environmental impact. Sixty companies have signed licensing agreements for the alloy, which was patented in 1996 and 2001, pushing royalties to $13 million. More of the alloy in electronic components means less lead ending up in electronic waste.

Yet Anderson’s work with the alloy is far from complete. Enhancing reliability is one of the next challenges; reaching that goal involves formulating new combinations and peering deeper into material characterization.

“I think we are at the point where we have tweaked the three-component (tin, silver, copper) alloy to a very good formulation that is most useful if you add one additional element into it,” Anderson says. “That additional element can control very closely how the solder joint solidifies so that it forms the best possible microstructure at the start of its lifetime.”

That fourth element—at least the one that Anderson is willing to disclose—is zinc. (There is another candidate, but he’s not talking about it just yet.) Zinc, Anderson explains, controls the original solidification of the joint and also seems to be the most effective at long-time, high-temperature aging conditions by maintaining the strength and ductility of soldered joints.

Anderson was recognized by the Iowa Intellectual Property Law Association as its 2006 inventor of the year, 10 years after the original patent. His research toward that first formulation had evolved from classical metal-lurgical training and close collaboration within Ames Lab. Today, however, his work benefits from the scrutiny of a wider research community. Published work from other laboratories and thermodynamic modeling at the National Institute of Standards and Technology have contributed to a growing body of knowledge.

“We’re taking that information and going further,” Anderson says, “so we’re a whole lot smarter than we used to be. Plus there is plenty of data that have been accumulated on reliability, and the community has been good about sharing it.”

Although reliability is foremost for the military and automotive customers of Anderson’s solder technology, he seeks to augment the performance of the solder in other ways. One project involves Nihon Superior, a Japanese solder manufacturer.

“We are looking at how we can design a solder alloy that works well with high-power electronics,” Anderson says, “preserving the audio quality of these very high-power devices.”

The work presents Anderson with new problems to solve and opens even more potential for the already successful solder. For example, he sees plenty of room for more detail in microstructural analysis, a line of pursuit that is more accessible as techniques and equipment become available. (See “Atom Probe” on back cover.)

“There’s alloy design space left that we haven’t even touched,” he says. “We’re surprised every day with new things.”

The motivation to improve upon a successful alloy goes beyond just scientific interest. Bringing lead-free solder to more companies and expanding its applications reinforce Anderson’s conviction that electronic waste is affecting the environment. He is not alone in holding that view. On July 1, 2006, the European Union began strictly limiting the amount of lead and other hazardous materials used in the circuitry of any electronic appliance sold. A similar approach is being taken in Japan.

“In the last half dozen years, more electronic trash has accumulated,” Anderson says. According to a 2005 U.N. report, up to 50 million tons of “e-waste” is generated annually, mostly in the form of computers and cell phones. As much as 70 percent of that ends up in China. Anderson has seen examples on various Web sites of it piled high—and out in the open—in some locations there. The biggest concern for any form of electronic waste is the potential for runoff into groundwater.

“We should not be adding to this,” Anderson says. “I think that in some small way here, we can have an impact on reducing the toxicity of that runoff.”

Perhaps more than just a small way. Anderson’s idea seems to have found its time, and the momentum is building.

“Probably one of the most active groups right now in one of the technical societies I belong to (Minerals, Metals, and Materials Society) is the community involved with lead-free solders,” Anderson says. “They’re driven. It’s a real exciting research environment, and there’s a lot of interest in every new development that comes along the way.”