Lead free: a weighty debate

Several months after the European Parliament approved stringent legislation banning lead and other hazardous substances in electrical and electronic equipment sold in Europe beginning July 2006, the industry is finding compliance easier said than done.

Though component suppliers are taking some initiative to offer parts with lead-free finishes, OEMs and EMS providers are leery of committing to them because of the logistical issues of identifying and qualifying environmentally compliant parts and the added cost of running multiple production lines to accommodate both lead-bearing and lead-free parts.

Compliance is also hampered by loopholes in the European requirements that exempt many products, as well as an absence of similar mandatory legislation in other world markets. Still lurking in the background are sceptics who insist the legislation is unnecessary because the detrimental effects of lead and other banned substances have not been clearly established.

Getting component suppliers and OEMs in sync on adopting lead-free assembly remains the biggest challenge, according to Thilo Sack, an advisory engineer at EMS provider Celestica, Toronto.

"Because you're getting various demands from the OEM, it makes it difficult for ourselves and component suppliers to say when we want to transition significant amounts of our production capacity to lead-free," Sack said.

"If you're looking at transitioning a product to lead-free, you have to understand your product development cycle and product validation cycle times."

For OEMs, those parameters vary not only by product but also by industry. The Restrictions on Hazardous Substances (RoHS) directive passed by the European Parliament covers five other substances besides lead but because lead is most prevalent in electronic assemblies, that sector has borne the brunt of compliance efforts.

The RoHS directive covers many consumer and household electronic goods, but exempts products sold to the automotive, medical, military/aerospace, and telecom infrastructure markets.

Similar legislation may be phased in to cover those industries later in the decade.

The lack of uniform environmental regulations in other regions has slowed compliance.

The US government has shown no inclination to legislate substance bans or recycling nationwide, though some states are implementing their own programs.

In Japan, the government has mandated that electronics manufacturers document lead content in their products. Though not subject to an outright lead ban, Japanese OEMs have shown initiative by phasing lead out of their products, often as a marketing tool, according to analysts.

US companies whose products are exempt from the RoHS requirements continue lead-free process development, anticipating they eventually must comply with an expanded lead ban. One such supplier is Delphi Delco Electronics Systems.

"We've seen a few more questions since the beginning of the year, but no significant lead-free conversion by our customer base," said a spokesman for the Kokomo automotive electronics vendor.

Another company exempt from the 2006 regulations, server OEM Storage Technology, Louisville, takes little comfort from having more time to study the situation.

"I view this as a hollow victory," said advisory engineer Richard Charbonneau. "I don't see how I can produce products in 2008 that use parts with leaded finishes as suppliers switch over to lead-free parts."

Charbonneau added that Storage Technology has not converted to lead-free assembly because of lingering concerns over problems like moisture sensitivity and tin whiskers - hair-like crystal structures that grow from tin-coated surfaces and are known to cause field failures.

When to switch?

EMS providers whose OEM partners are affected by the 2006 deadline are scrambling to shore up procurement, inventory, and production practices to deal with both leaded and lead-free parts at the same time.

"There will be lots of scrubbing of bills of materials, " said Kim Hyland, director of process integration at Solectron, Calif. "What we've been seeing is process change notices by suppliers ready to ship lead-free components." To ensure more uniform parts quality, Solectron is encouraging suppliers to comply with solderability testing guidelines it has developed based on JEDEC J-STD-020B. "We're trying to make sure we don't get different testing for different components," said Jasbir Bath, an advisory process engineer at Solectron. "We want to relate to the standards available."

One issue suppliers are addressing is simply to make lead-free parts available.

For instance, Texas Instruments now makes all its logic parts available with a nickel-palladium-gold or tin-silver-copper finish, according to David Hoover, worldwide product marketing manager for the linear and logic group at the Dallas-based semiconductor supplier.

"What we're seeing is that product requirements are moving higher," Hoover said. "We're changing our products to comply with the 260°C temperature required for lead-free soldering."

Hoover said the logic devices would be priced equivalent to leaded parts with a two week lead time. To ease the transition, TI will continue to offer tin-lead finishes on some parts, particularly those in BGA packages.

Similarly, flash memory supplier Silicon Storage Technology, Calif, expects to offer both lead-bearing and lead-free parts for the foreseeable future. "Our customers are transitioning over as far as we thought they would," said Sirak Brook, marketing manager for the standard memory product group. "We've seen demand increase since 2002, but by no means is it near a substantial part of our business."

The company now offers 85% of its parts with lead-free finishes, Brook said, and plans to qualify flash parts in SOIC, stacked TSOP, and stacked-die BGAs in the second half of 2003.

Can it be done?

Storage Technology's Charbonneau is sceptical about whether suppliers, despite their stated intention to offer both leaded and lead-free parts, can afford to do so over what's likely to be a transition period lasting several years.

"I don't think it's economically feasible for suppliers to maintain both leaded and lead-free parts," he said. "I've been told by suppliers they want to settle on a single finish."

The slower conversion of some components to lead-free finishes is not helping matters, according to EMS providers.

"We've found most components are suited to convert to lead-free, but LEDs and some capacitors are a problem at higher temperatures," Solectron's Bath said.

Celestica's Sack said, "We have trouble now handling film capacitors, magnetics and optical devices. If you're talking about elevating temperatures, there are additional challenges."

Sack said OEMs are reluctant to convert because they don't want sole-sourced parts or constant bill of materials changes. "Whenever you make a change to the assembly, you have to requalify the entire assembly," he said, adding that "customers want to come out with a total lead-free solution."

Trust the supplier

In some cases, suppliers say OEMs need to place trust in them for products where customisation makes second sources difficult to provide.

"Our industry has no second sources," said Jon Ewald, director of product marketing at Actel, a Sunnyvale supplier of FPGAs. "The customer needs to make a decision on the product up front."

Actel expects to offer lead-free package options for all its FPGA packages by the end of this year.

"We have seen an increase in enquiries and are starting to see our first demand in Japan and Europe, though customers are not ready to place orders yet," Ewald said.

As suppliers convert their parts to lead-free finishes, users also worry they won't easily be able to differentiate between lead-free components and their lead-bearing counterparts, creating possible soldering problems because lead-free process temperatures are higher.

Both Silicon Storage and TI said they would designate their lead-free parts differently to leaded devices.

Another supplier, Vishay, expects to add a suffix to identify its lead-free tantalum chip capacitors when they are available by year end, according to Dave Richardson, director of marketing for moulded and leaded tantalums.

Another passives supplier, AVX, is retaining the same part numbers for its tin-plated tantalum capacitors while it phases out tin-lead versions, said applications manager Chris Reynolds.

Because the tin-plated parts are fully compatible with existing vapour-phase or infrared reflow soldering, the transition is seamless for the user, he said.

Identifying lead-free parts will likely became a thornier issue as more become available, according to Celestica's Sack.

"Component suppliers don't want to change part numbers," he said. "There's no industry spec to identify lead-free parts, though some standards groups are trying to come up with a universal marking scheme."

OEMs also have to bear additional production costs during the lead-free transition. Patrick Le Fevre, director of marketing at Sweden's Ericsson Microelectronics, said the company is running two lines - one for leaded parts and the other for lead-free devices at its plant in China, where DC/DC converters are made.

"We have an aggressive program to convert, but market requirements for lead-free products remain soft," Le Fevre said.

The lead-free movement has also altered procedures for semiconductor assembly and test service providers like ASE, Taipei, Taiwan. The company has had to buy different moulding compounds and substrates and stock more parts.

"We have 155 packages either already qualified or undergoing qualification," said Bill Chen, senior technical consultant. "A lot of customers are now going into qualification.

"Making packages lead-free is not an easy thing to do. Each package represents a lot of manufacturing, engineering and materials effort," Chen said.

In addition to the lead-free requirements, the electronics industry also has to comply with the WEEE (Waste Electrical and Electronic Equipment) directive passed as companion legislation to RoHS.

The WEEE directive requires that OEMs take responsibility for recycling products. However, it does not address how OEMs would collect consumer products that the directive targets, according to LeFevre.

"The real concern is handsets and consumer products," he said. "There's no regulation requiring that the consumer return the product for recycling. It's not clear how the products will be marked and identified."

LeFevre added that imposing a deposit fee that would be refunded to users when they recycle the products is a possibility, but nothing has been decided yet.

Where's the evidence?

Though the electronics industry generally concedes it must comply with more stringent environmental regulations, an air of dissent remains among some who say scientific evidence to justify the laws is insufficient.

Gordon Davy, an engineer for Northrop Grumman Electronic Systems, Baltimore, said the military/aerospace sector, whose products are also exempt from the 2006 deadline for the RoHS directive, could be adversely affected if the industry moves from using tin-lead solder to alternative finishes such as pure tin or tin-bismuth.

Davy contended that scientific data documenting the harmful effects of lead content in electronics has not been clearly established. He said quality problems could arise from the use of alternate materials, such as pure tin plating, which increases the risk of tin whiskers, and tin-bismuth, which can reduce solder joint strength.

"If lead was bad for the environment, somebody would have stepped forward to show how bad it is," Davy said.

Joseph Fjelstad, founder of Silicon Pipe, a San Jose supplier of IP for copper-based packaging technology, agreed.

"No evidence has ever been produced to prove lead in electronics is a risk to human health," Fjelstad said, noting that the RoHS legislation came about after fears of lead poisoning prompted industry officials to infer a danger from electronics even though no clear link exists.

The IPC, an industry trade group, has noted that the US electronics industry is responsible for less than 2% of global lead consumption, and that the lead used in manufacturing and electronics assembly produces no significant environmental or health hazards.

The group, however, said it supports a global effort by both legislative and market forces to resolve environmental compliance issues.