RoHS era drives changes in design priorities

Months after the enforcement of the European Union's ban on the use of six environmentally unfriendly materials, designers have clear evidence that failure to meet the Restriction of Hazardous Substances (RoHS) directive means lost sales.

Palm Inc. recently announced that its Treo 650 smart phone is no longer being shipped to Europe, since it doesn't meet RoHS requirements. And several Apple Computer Inc. products will not be sold in Europe for the same reason. According to a June report in AppleInsider, these products include the iSight Web camera, AirPort base station with modem, AirPort base station power-over-Ethernet and antenna, iPod Shuffle external battery pack, and all versions of the eMac all-in-one desktop computer. However, the latest-generation iPod, iPod Nano and iPod Shuffle all meet the RoHS regulations.

The EU directive, which took effect July 1, covers lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers. Electronics vendors worldwide are working to eliminate those substances from nearly all new products developed for the European market, while also adapting their manufacturing processes to a lead-free environment.

Major concerns will run the gamut from finding component databases of qualified green components to undertaking due diligence to prove compliance and developing processes that allow for the higher-temperature requirements of lead-free manufacturing. And for designers, those are just the tip of the iceberg. A host of nagging technical and reliability issues remain to be sorted out in lead-free board processing and soldering.

Manny Marcano, president and CEO of EMA Design Automation Inc., cited the impact of parts obsolescence, including the need to redesign older products and the resultant emphasis on component engineering at the expense of conceptual design. A key challenge is identifying RoHS design specifications as early as possible in the design process, he said.

Cost of non-compliance
If designers don't take RoHS seriously, any country that can prove a product does not comply can levy fines against the vendor. That can cost market share, Marcano said, since non-compliant companies become non-competitive ones. And then, being unprepared can mean belatedly diverting resources to RoHS compliance, causing missed market opportunities.

The product developer's RoHS concerns center on the fear of lost revenue—from a product ban, a customer who demands a RoHS-compliant product that the company doesn't have, or competition, said Harvey Stone, managing director for consultancy GoodBye Chain Group. "With price, quality and service being relatively equal, a savvy customer is going to choose an RoHS-compliant product," he said.

Meanwhile, designers are looking over their shoulders at several other—and potentially stricter—environmental regulations in the pipeline. These include the EU's Registration, Evaluation and Authorization of Chemicals legislation, which could restrict the use of thousands of chemicals, and its Energy-using Products directive, which will initially target energy-efficiency requirements.

RoHS restricts six hazardous substances.

If these new environmental rules are posing challenges for global businesses and the global supply chain, they are also driving changes at the design stage like nothing else before them, say industry players.

"RoHS is geared toward the design stage of the product life cycle to reduce environmental issues by requiring designers to design down, if not out, the use of the six nasty substances," Stone said. To do so, they must consider other design criteria, including form, fit, function, cost and marketability, he said. "In many cases, this is the first time designers have had to design-in toxicity requirements as a design parameter."

Toxicity may be the most important environmental parameter today, but in the coming years, designers will also have to wrestle with energy efficiency, a product's recyclability and amount of recycled content, and materials reduction.

Many designers—particularly those at smaller companies—are just getting started on the road to compliance. "Being RoHS-compliant or not needs to be a product requirement from the start because everything you do from that point on supports that decision," said Ken Stanvick, senior VP at Design Chain Associates.

Process changes
Leaded vs. lead-free makes a difference in assembly temperatures and process capabilities, said Robert Chinn, director for consultant firm PRTM. And since many companies are running both leaded and lead-free lines, designers have to ensure the right processes are in place so there will be no mixing, Chinn added.

Designers, said Stone of GoodBye Chain Group, "need to know that lead-free parts need to be manufactured at higher temperatures. They should also know the performance characteristics of alternatives to mercury or hex chromium, as well as of lead-free solders, when designing a circuit. They also need to be aware of processing temperatures and moisture-sensitivity levels."

For hybrid assemblies, one of the biggest design challenges involves legacy components, including capacitors and resistors that were already compliant, but weren't capable of handling the new processing temperatures, said Joe Scala, director of global RoHS implementation for Celestica. "They were rated for 230°C, the old Jedec standard, vs. 260°C required for lead-free," he said. "They're great from an RoHS perspective, but not so great from an ability to process them down the line using a SAC tin-silver-copper alloy."

Other obstacles involve materials selection, reliability, board layout and pad sizes, Stanvick said. Boards may require additional support when reflowed, and the higher temperatures will make them warp more easily, he said. In addition, there is the cost of materials, qualification and requalification.

There is also talk about changing the pad sizes on the boards. "The lead-free solder doesn't flow out as well, and in some cases you may see some exposed copper because it has different cooling characteristics," said Stanvick. The industry organization IPC has released the IPC-610 specification, with a new set of inspection criteria that designers need to be aware of, he said.

- Gina Roos
EE Times