Leaded Parts Still in High Demand

Most electronic components are now lead free. Yet even in a post-ROHS world, components that contain lead are in high demand. Industries such as defense, aerospace, and medical equipment are currently still exempt from government legislation calling for lead free parts. And these exempt industries need highly reliability parts that come with lead solder and coatings. The components industry, however, has shifted overwhelmingly to lead free parts, leaving the exempt industries scrambling to find parts that still contain lead.

For decades, defense and aerospace manufacturers used COTS (commercial-off-the-shelf) components. They were both cheap and reliable. These components had decades of field testing, so manufacturers that require high reliability parts were comfortable using commercial parts even in the high stress environments of space and military settings. The parts held up.

Lead free components don’t inspire the same confidence because they haven’t been subjected to years of field testing. Plus, tin solder without a small portion of lead can grow tin whiskers in extreme environments. When those whiskers break off, they can short out, causing the system to fail. "There are quality concerns about lead-free components because they have not been field-tested for a long time,” said Dennis Zogbi, CEO of Cary, NC-based market researcher and business consulting service Paumanok Publishing Inc. "Components that go into an airplane have to be robust. They have to be tested for high vibration over a long time.”

The exempt industries need parts that can perform reliably in extreme environments. In the 1990s, a multi-million dollar communications satellite went dark after a few short months of service. Most engineers blame the malfunction on component failure. When it comes to airplanes, military systems or life-supporting medical equipment, there is little room for risk. "The critical concerns are hot and cold temperatures, corrosion and vibration frequencies,” said Zogbi.

For commercial applications, lead free components are plenty reliable. Tin whiskers are not likely to grow on the components in your cell phone or television. Plus, consumers don’t expect a commercial electronic product to last more than a few years. In military and space applications, however, systems have to last decades, facing extreme weather, temperature and vibration.

The need for leaded parts
When the major component manufacturers switched to lead free parts, some manufacturers in the exempt industries switched to the lead free components simply because the leaded versions were no longer available. "Most companies in the exempt industries are using COTS parts,” said Gary Nevison, Legislation and Environmental Affairs Manager at Newark. "They’re using lead free components primarily because nothing else is available. But they take additional precautions to ensure high reliability.”

One of those additional precautions is dipping lead free components in lead to enhance reliability. "There are various mitigation strategies designed to make lead free finishes less of a problem,” said Bryan Brady, VP of the Defense and Aerospace Business Unit at Avnet Electronics Marketing in the Americas in Phoenix. "Solder dipping is good, but it’s expensive.”

The solder dipping process is typically done by a third party company and affects the warrantee of the component. Component manufacturers don’t want to ensure the reliability of a part that has been altered. To bring down the cost of solder dipping, engineers are looking into the possibility of using robotics to automate the labor intensive process. Avnet is also considering a move to dip components in volume to reduce costs.

The components industry is also trying to solve the reliability challenge by developing alternatives to pure tin solder. Lead was originally added to tin to mitigate the tin whisker problem. Other metals, such as gold, silver, and nickel, have been tested as lead replacements. "People have done a lot of work developing mitigation strategies such as evaluating lead free finishes that are less of a problem,” said Brady. "Plenty of people are spending their careers on this topic.” These efforts have met with success, but they tend to be expensive.

Price of leaded parts increases
Because leaded parts are not being produced in large volume, cost has become a major issue. There are very few sources for leaded parts. One disappearing source is old inventory. As companies comb the world for older parts, they run the risk of counterfeit components. "Counterfeiting is a big issue,” said Paumanok's Zogbi. "There isn’t enough manufacturing of leaded parts in North America.” So manufacturers go to Asia, where "one out of 10” of the components they find are counterfeit.

Another alternative to COTS components is "mil spec” parts. Mil-spec components consist of parts produced in small qualities specifically for military specification. They’re certainly reliable, but they’re pricy. "Mil-spec is still a robust business, driven by legacy systems,” said Avnet’s Brady. "But from a design point of view, the costs are overwhelming.” Mil-spec parts are produced in small quantities, so the high pricing is not likely to come down. "For the most part, only about 5 percent of our design is mil spec, and that’s mostly for space applications,” said Brady. "Ninety five percent of our components are for commercial applications.”

One of the problems with leaded parts is they’re old. Component manufacturers are not designing new leaded parts, so the leaded parts that remain don’t include new design features. "Leaded components are not just leaded, they’re also obsolete,” said Daren Saroop, Director of Sales at Virtual Chip Exchange Inc in Hauppauge, NY. "They’re good quality parts, but the design hasn’t changed.”

Saroop sees considerable demand for leaded inventory. "We’re accumulating inventory of leaded parts for people to use in their older products. It’s massive,” he said. Part of the demand comes from the fact that many of the older components are not being made in a ROHS-compliant version. "The old parts are not necessarily being replaced by lead free versions,” said Saroop.

Many in the component industry believe the difficulty in finding reasonably priced, high reliability parts will eventually be solved with lead free parts. At some point companies will view lead free parts are sufficiently tested and reliable. "People are gaining confidence in lead free components,” said Brady.

That confidence is likely to grow as component manufacturers gain more experience in producing lead free parts. "I think lead free components will continue to improve,” Brady continued. "For most of our customers, lead free is no longer an issue.”

Electronic Business, a sister publication of EM Asia