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Designing and shipping after RoHS

Posted: 23 Aug 2006 ?? ?Print Version ?Bookmark and Share

Keywords:European Union? RoHS? Palm? Apple Computer?

Almost two months after the European Union's ban on the use of six environmentally unfriendly materials went into effect, designers have clear evidence that failure to meet the Restriction of Hazardous Substances 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, they include the iSight Web camera, AirPort basestation with modem, AirPort basestation 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 Pb-free environment.

But that's only the beginning. Other countries, including China, Taiwan and South Korea, and certain U.S. states are creating their own "green" or RoHS-like legislation. That means RoHS compliance must become an integral part of a designer's development process, with RoHS checks at each step: concept, development, prototype, first builds and volume production.

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 Pb-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 Pb-free board processing and soldering. Otherwise, such annoyances as tin whiskers and copper dissolution could hamstring manufacturing and require rework. (Tin whisker growth has been linked to failures caused by electrical shorts; copper dissolution affects the reliability of solder joints.)

What it comes down to is what Ken Stanvick, senior vice president at Design Chain Associates, calls a lack of "tribal knowledge" on design RoHS-compliant systems. "We had a great tribal knowledge when it came to dealing with leaded systems, but we haven't built up that same amount of knowledge for Pb-free," he said. "Every problem will be blamed on Pb-free until it's been worked out. We need to figure out tests that replicate more of the environment and different stresses that we're going to see in this new system."

Manny Marcano, president and CEO of EMA Design Automation Inc. (Rochester, N.Y.), 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.

But even before they get to that point, designers must understand whether they are designing a fully compliant product or one that's subject to some exemptions, said Robert Chinn, director for consultant firm PRTM (Mountain View, Calif.). "This factors into their design parameters," he said. "Previously, they looked at components based on size, performance, electrical parameters, features and functionality. Now they have to add on a new requirement, revolving around environmental compliance: Is it RoHS 6-compliant or is it RoHS 5-compliant?" (RoHS 6 components eliminate all six of the banned substances, while RoHS 5 models, because of exemptions, still contain lead.)

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 noncompliant companies become noncompetitive one. And then, not being prepared can mean belatedly diverting resources to RoHS compliance, causing missed market opportunities.

The moral of the story? "An engineer needs to instantiate the compliant data at the conceptual design stage in order to decrease risk downstream," Marcano said.

But many industry observers believe smaller and medium-size companies will continue to be complacent about the RoHS transition until some major company is cited for noncompliance. "When that happens, there will be an earthquake throughout the industry, and it will wake up every design engineer," said Steve Schultz, director of strategic planning and communications at Avnet Logistics and program manger for the distributor's compliance efforts for RoHS in the Americas.

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 (Colorado Springs, Colo.). "With price, quality and service being relatively equal, a savvy customer is going to choose a 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 (EuP) directive, which will initially target energy-efficiency requirements.

"EuP is an order of magnitude more complex than RoHS and WEEE [the EU's Waste Electrical and Electronic Equipment directive] in terms of what it requires of companies," said Stone. "This will cause a larger problem for designers because they will have to account for more environmental parameters when they design new products."

If these new environmental rules are posing challenges for global businesses as well as 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 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 Design Chain Associates' Stanvick.

At this first step, the challenge is determining whether a product falls outside the scope of the RoHS directive; if so, it is exempt from complying with the requirements. Joanne Volakakis, director of marketing for catalog distributor Newark InOne, said customers are still asking whether they need to be compliant. "It's typically the engineers at small-to-midsize companies that are asked to figure it out," she said.

It's also important to remember that RoHS brings some advantages along with the headaches, said Stanvick. He noted that manufacturers may realize possible savings by improving sloppy processes to make them consistent and by reducing material sets. "For example, the use of recycled plastics costs, on average, about 80 percent less than [using] virgin plastics," Stanvick said. "If you do a good job on the front end, you make everybody's job downstream easier."

Distributor field application engineers (FAEs) can help customers with the RoHS transition, but they have to be educated first about the mechanical and manufacturing obstacles, said Theron Makley, director of engineering at Arrow Electronics Inc. (Denver). FAEs are typically EEs who make product recommendations to their customers based on electrical specifications. "Because of this RoHS change, we've had to educate our engineers so they become adept at informing our customers about [RoHS] manufacturing methods and [making the customers] aware that there could be issues with switching over," Makley said.

One element needed for a successful transition is a design methodology that can help designers comply with mandatory requirements, from component selection to proof of compliance. Products in this category are beginning to appear on the market. One example is EMA's Engineering Data Management system, which enforces a "compliance by design" process that can be deployed locally or globally.

While the specific design automation tool usage is important, the actual deployment and implementation of the tool set is the key to success, EMA's Marcano said. "Anyone can design with compliant parts, but the real objective is to be able to prove to the enforcing authority that you have done your due diligence regarding compliance." The EMA tool generates a compliance assurance system that is said to track the product all the way from concept to proof of compliance.

Process changes
On top of dealing with the many design challenges of RoHS, engineers must be aware of how their RoHS-compliant designs are manufactured. Design engineers "are no longer just thinking about the design electrically," said Paul Peterson, senior FAE for Arrow Electronics. "They are also thinking about manufacturability, more so than they had in the past."

Leaded vs. Pb-free makes a difference in assembly temperatures and process capabilities, PRTM's Chinn noted. And since many companies are running both leaded and Pb-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 Pb-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 Pb-free solders, when designing a circuit. They also need to be aware of processing temperatures and moisture-sensitivity levels."

One way to avoid some problems often associated with Pb-free processes-such as cracking, delamination and joint reliability-is to make sure board qualifications are performed prior to product builds. Also, all supply chain partners need to educate themselves about the Pb-free environment in order to distinguish between what is a defect and what isn't. Discerning actual problems in this environment is the hardest thing to do, said Gail Auyeung, global commodity engineering adviser for printed-wiring boards at Celestica Inc.

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 degrees C, the old Jedec standard, vs. 260 degrees C required for Pb-free," he said. "They're great from a 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.

The higher process temperatures also mean problems with thermal-glass temperatures of the epoxy used on the board, as well as the coefficient of expansion, thermal decomposition, said Stanvick. Also, vias may crack due to thermal stresses being applied to the board, he said.

There is also talk about changing the pad sizes on the boards. "The Pb-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

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