Electronic Design

Time Is Ticking... Lead-Free In A Year Or Else

Most companies are responding to the European directives to remove lead (and other toxic substances) from their products, while others still try to figure it out.

For most of the industry, lead-free means home free. At least for a while. You have likely heard by now that the European Union (EU) adopted a new directive called Restrictions on Hazardous Substances (RoHS). It eliminates or significantly reduces the use of certain substances from electronic products beginning July 1, 2006.

If you haven't already done so, now might be a good time to remove most of the lead (Pb), cadmium (Cd), mercury (Hg), hexavalent chromium (Cr VI), and all of their compounds, as well as polybrominated biphenyl ethers (PBBs) and polybromobiphenyl (PBDEs), from your products.

And that may be just a starter list. Industry companies, mostly OEMs, have been sending detailed questionnaires to their suppliers, mostly chip manufacturers, asking about other chemical substances used in their products, suggesting that the restricted-materials list will expand.

Most OEMs, which are ultimately responsible for complying with RoHS, take the directive very seriously. But many still wonder how the legislation will impact their company. RoHS seminar attendees continue to ask what all of this means to them.

"The devil's in the details," says Max Elbaz, general manager of Underwriters Laboratories' UL RSCS Program, which offers a comprehensive testing and surveillance program.

Cindy Newell, tactical marketing manager at programmable-logic specialist Actel and the company's resident lead-free/RoHS expert, says that there's "still a lot of confusion and some issues still need to be clarified." Due to RoHS's complexity and the fact that it's still a work in progress, she says Actel anticipates "a flurry of activity just before the deadline, with people saying 'we need these devices right now.'"

Leonie Tipton, Arrow Electronics' vice president of supply-chain programs, says that most OEMs are at the "we know enough to act" stage. But does this mean that all OEMs will comply with RoHS by the July 2006 deadline?

"They will have to," says Elbaz. Aside from the potential loss of sales, companies attempting to deliver noncompliant products also face criminal and civil penalties. Sanctions will probably be handled country by country in the EU. Elbaz says that companies that don't comply may see a negative impact on their brands and corporate images. Electronic-manufacturing-services (EMS) companies are being particularly cautious with their suppliers and customers.

"Let's say an OEM's product gets stopped at the border, and they start doing supply-chain detective work to figure out where the noncompliant component came from, and what due diligence was done in order to ensure that the product was compliant," says Art Morgan, director of technical marketing at Solectron. "It is the supplier's responsibility to come back to the OEM and ourselves with information about that component."

Solectron is asking its suppliers to do a full chemical analysis and provide the weights of each substance. "The integrity of the data is the supplier's responsibility, and we're putting language in our contracts that assign liability to them," Morgan says. The detective work probably will "be driven by OEMs because their neck is on the line."

"Small EMS firms have no control over this," says Steven Schmidt, president and CEO of APSCO. "We're caught in the middle. We must build to print." Schmidt estimates that 95% of EMS companies with revenues under $200 million still aren't RoHS-ready. Perhaps worse, he says, "We're getting data from customers to build lead-free assemblies that we don't feel is adequate. We need a paper trail to protect ourselves. We have to verify that the parts we're supplying are lead-free-compliant."

GETTING WITH THE PROGRAM
OEMs, particularly the larger ones, got the message a long time ago, and they're responding. Hewlett-Packard doesn't use some of the substances restricted in RoHS, but it updated its General Specification for Environment to include interim RoHS language. HP shipped its first RoHS-compliant components in 2004, focusing on converting families of component parts as opposed to single products or platforms. HP expects to be fully compliant globally by the RoHS deadline (see the figure).

Dell first formally addressed the issue more than a year ago. At that time, Dell called the directive—in boldface type on its Web site—"a significant challenge for the electronics industry" that "involves a complex set of technical attributes that have yet to be standardized."

IBM responded, in part, by adding elements of the RoHS directive to its international parts management relational database (IBMParts). It now collects data on customer-designated restricted and reportable materials, as well as RoHS attributes and exemption eligibilities.

When Sony launched its GreenPartner supply-chain management program in July 2001 to prequalify vendors under its strict environmental policies, RoHS wasn't in the plan. That changed, Sony executives pointed out at the recent IEEE International Symposium on Electronics and the Environment, when the company started spot-checking its game consoles shipped to the Netherlands.

Sony found cadmium contamination in flexible cords purchased from a supplier, forcing the company to suspend shipment of the unit for several weeks. As one of the Sony executives explained at the IEEE symposium, "The incident opened the eyes of management to the magnitude of the issue." Sony now uses GreenPartner to certify products for RoHS compliance.

EYE ON JAPAN
Many Japanese OEMs have mandated lead-free components for two to three years. "Japan has taken more of a leadership position in creating a lead-free environment," says Greg Takagi, director of global environmental health and safety at International Rectifier. "The industry in Europe followed fairly quickly."

Takagi says that IR, like many other component manufacturers, is being asked to sign off on 75 to 100 certification documents a month from customers, attesting to the lead-free status of its products. Takagi says, "We are targeting compliance well ahead of the RoHS deadline, so that our customers will have sufficient time to design and qualify our parts into their products before the July 1, 2006 deadline."

TIN WHISKERS
Lead is garnering the most attention because it affects the most manufacturers. But not everyone is taking the same approach in selecting an alternative material.

A majority of chip packages being shipped now use a layer of tin and lead over copper. As companies move toward lead-free devices, many of these packages will use a combination of tin over copper, processed at temperatures significantly hotter than packages with lead in them.

For example, lead-free solder systems typically run at temperatures between 30°C to 50°C higher than lead-based systems. But some commercially available tin-over-copper packaging can form "whiskers"—electrically conductive crystals of tin that grow spontaneously from a tin-plated surface.

As the whiskers grow, they can create electrical shorts or break off and cause other system failures. Satellites have become the "poster child" for tin whiskers. Over time in outer space, they can experience large swings in heat that blow out components. This phenomenon could ultimately cause billions of dollars in satellite damage.

Matte tin seems to be the lead-free alternative of choice for most component suppliers. However, Agere Systems has been shipping lead-free devices using a layer of nickel between copper and a layer of tin. The company claims this method offers dramatic improvements over matte tin, based on two years of testing against matte tin.

"Some customers who have done some sampling and run their own tests have also seen whiskers with matte tin parts," says David Miller, Agere's director of assembly and test sources. "Over time, they continue to grow."

National Semiconductor, which plans to be totally RoHS-compliant by the end of June 2006, replaced the lead in leadframe packages with a matte tin finish. It also swapped out the lead in solder balls for a tin-silver-copper alloy in micro SMD and tin-silver in PBGA and FBGA packages. Once its program is fully implemented, National says it expects to eliminate approximately five tons of lead per year.

With more than 35,000 components in its product portfolio, Toshiba America Electronic Components is using a variety of lead-free alternatives depending on the product, country of manufacture, cost, materials availability, and thermal environment requirements. Toshiba offers six primary alternatives: tin-silver, tin-silver-copper, nickel-palladium-gold, gold, silver, and tin-copper.

Pulse/Technitrol, a specialist in passive, magnetics-based components, utilizes a matte tin finish with nickel underplate and a hot-dip process for 100% tin lead plating.

Vishay Intertechnology's new ACAC 0612 resistor arrays are now lead-free. The company says the pure-tin plating is compatible with lead-free and lead-containing solder processes. It also says extensive testing has proven the immunity of the plating against tin-whisker growth. The resistor arrays comply with the CEFIC-EECA-EICTA list of legal restrictions on RoHS hazardous materials.

Dick Bowyer, the lead-free specialist for connector manufacturer Samtec, says his company has significant field experience with pure-tin plating over nickel underplating and hasn't seen any reports of tin whiskers with this plating combination. The only whisker testing being performed by Samtec is for firms with specific test criteria. The results of these tests are proprietary to the companies requesting the tests.

Distributor Newark InOne says that while chemists and metallurgists pursue new technologies to limit whiskering, the success of these efforts is uncertain and may not be available for some time. Yet the International Electronics Manufacturing Initiative (iNEMI), an industry-led consortium focused on strengthening the global electronics manufacturing supply chain, released two documents to help manufacturers reduce the risk of tin whiskers in lead-free products.

The first is JEDEC standard JESD22121, "Test Method for Measuring Whisker Growth on Tin and Tin Alloy Surface Finishes." The other is the updated "Recommendations on Lead-Free Finishes for Components Used in High-Reliability Products" from the iNEMI Tin Whisker User Group.

The JEDEC standard details a suite of tests that provide an industry-standard method of measuring and comparing whisker propensity for different plating or finish chemistries and processes, a consistent inspection protocol for tin-whisker examination, and a standard reporting format.

Based on data from around the globe, plus extensive testing by iNEMI members and others, the JEDEC standard identifies three test conditions that appear suitable for monitoring tin-whisker growth. Two provide for isothermal conditions with controlled humidity. The third is a thermal cycling condition.

JESD22A121, which was developed by the JEDEC JC-14.1 Subcommittee on Reliability Test Methods for Packaged Devices, can be downloaded for free from the JEDEC Web site at www.jedec.org or http://jedec.org/download.

UNIQUE PART NUMBERS
Because of the complexity of the industry's distributed design and manufacturing supply chains and the incompatibility between current tin-lead (SnPb) and RoHS-compliant products, creating new part numbers for lead-free components has become a major issue in RoHS compliance. "Everyone is doing it differently," says Actel's Cindy Newell.

According to iNEMI, most OEMs and contract manufacturers strongly support the use of unique part numbers for RoHS-compliant components. "Many of our members feel very strongly about this issue," says Jim McElroy, executive director and CEO of iNEMI. These members have asked the organization to issue a position statement supporting separate part numbers for compliant and noncompliant parts.

The iNEMI-developed position calls for manufacturers to know exactly what's in their products. In addition, they need a way to not only track, but also prove, their products don't contain lead, cadmium, or any of the other RoHS substances over the specified limits. "Separate part numbers will go a long way toward helping them make those assurances," says McElroy.

Intel plans to require its suppliers to change part numbers when they transition to RoHS-compliant parts and follow the established change control process. Vivek Gupta, program manager for Intel's Assembly Technology Division, says his firm expects its suppliers to mark their RoHS-compliant products per established JEDEC/IPC standards and implement controls to prevent mixing of RoHS-compliant parts.

And while the EU directive has been a work in progress for years, there are still kinks to be hammered out. One is harmonizing the legislation across industries. The automobile industry, the largest user of steel, for example, is working toward compliance with the EU's End-of-Life (ELV) directive. This act requires the elimination of hexavalent chromium in auto manufacturing beginning July 1, 2007, a year after the RoHS compliance date.

In one of its position papers, HP says the electronics industry buys a very small fraction of the total coated steel produced. Consequently, there's little leverage with suppliers to drive an earlier transition. To harmonize legislation across industries, HP has been working with others in the industry to request a one-year extension from the restriction of hexavalent chromium for electronics manufacturers. HP also is helping lead an industry effort to find practical alternatives to the hexavalent chromium coatings by sharing test results and establishing common specifications.

MORE TO BE DONE
In its 2004 Environmentally Conscious Electronics (ECE) Roadmap, iNEMI urges designers to develop a comprehensive and standardized framework or "quick reference" system to determine the environmental status of any substance (see the table). The group also suggests that data on product performance and compliance standards be available to ensure common interpretation and execution of design objectives that are driven by public policy.

One possibility would be to drop some parts if run rates are significantly reduced, rendering some chips obsolete. Most chip suppliers generate monthly forecasts. But that could change with suppliers conducting real-time market research simply by frequently interviewing their customers.

Some things are certain. Products will change, part numbers will change, and at some point, prices will change. As pc-board specialist Sierra Proto Express says so succinctly in one of its ads, "Ready or Not, Here Comes the Lead-Free Compliance Deadline."

NEED MORE INFORMATION?
Actel Corp.
www.actel.com

Agere Systems
www.agere.com

APSCO
www.apscoinc.com

Arrow Electronics
www.arrow.com

Artesyn Technologies
www.artesyn.com

Dell
www.dell.com

Hewlett-Packard
www.hp.com

IBM
www.ibm.com

Intel
www.intel.com

International Electronics Manufacturing Initiative
www.iNEMI.org.cms

International Rectifier
www.irf.com

National Semiconductor
www.national.com/packaging/leadfree

Newark InOne
www.newark.com/service/rohs/tin_whiskers.html

Niton LLC
www.niton.com

Omnify Software
www.omnisoft.com

Pulse/Technitrol
www.pulseeng.com

Samtec
www.samtec.com

Sierra Proto Express
www.protoexpress.com/leadfree

Solectron
www.solectron.com

Sony
www.sony.com

Synapsis Technology
www.synapsistech.com

Texas Instruments
www.ti.com/productcontent

Toshiba America Electronic Components
www.toshiba.com/teac

Underwriters Laboratories
www.uluniversity.com

Vishay Intertechnology
www.vishay.com

TAGS: Components
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