THE ALTERNATIVES
Most RoHS-compliant pc-board manufacturers admit they were still working and reworking their board designs and materials formulations prior to July 1 and probably will continue to do so for some time.
Jeff Schafer, senior vice president-product at components and test equipment distributor Newark InOne, says the availability of a wide range of new alloys with a variety of surface compatibilities, finishes, and process temperatures is causing a lot of market confusion. Larry McQuinn, vice president of sales and marketing of pc-board maker Advanced Circuits, also sees confusion from customers who think that as long as the finish on the board is lead-free, they’re in compliance. “They haven’t given enough thought to the assembly of the board,” he says.
Bath suggests board designers label their design drawings with the “e” code designation to indicate the type of lead-free solder to be used on the board. “This helps identify the correct lead-free solder to use for assembly, rework, and field return repair operations,” he says. (Details on code designations are available in the JEDEC DESD-97 and IPC 1066 standards.)
Further complicating the transition to lead-free components, McQuinn says, is that some assembly processes require high cycling temperatures that may call for different types of laminates than designers have been used to. “So, there’s still some confusion in the industry about temperatures in producing lead-free pc boards,” he says. The problem in replacing the lead in solder alloys with other elements is that lead-free alloys melt at a higher temperature than traditional tin/lead alloys. A 60/40 tin lead mixture melts at around 180°C (356°F), compared with 227°C (441°F) for lead-free.
The defense and aerospace industry sectors, which are exempt from the lead-free restrictions under RoHS, ironically may have the toughest time adjusting to the new legislation. Both industries want to avoid lead-free products because they believe they’re susceptible to tin whiskers growth, which could eventually hinder the performance of their products or systems.
With most chip suppliers switching over to lead-free devices, it may be increasingly difficult for the defense and aerospace industries to obtain leaded parts. Still, some chip and pc-board manufacturers will continue to run leaded lines for exempt applications, at least until demand begins to wane.
Two organizations, JEDEC and IPC, have released two documents to help manufacturers reduce the risk of tin whiskers in lead-free devices. JEDEC standard JESD201 and JP002, a joint publication of JEDEC/IPC, were developed specifically to help address mitigation practices, process controls, and verification testing in lead-free devices. Both documents can be downloaded from JEDEC’s Web site.
Also, the United Kingdom’s National Physical Laboratory (NPL) has published nine separate reports based on research sponsored by the European Lead-Free Soldering Network that deal with lead-free soldering in electronic components. The reports can be downloaded for free from the NPL Web site at www.npl.co.uk/ei/publications.
TI GETS A RUNNING START
Texas Instruments got an unexpected jump on much of the industry when it started producing lead-free nickel-palladium-gold components in 2000, mainly because they were similar in structure to the parts TI was already making. TI found that adding gold to the process gave the material some advantages.
“Having a whisker-free solution is a tremendous advantage right now,” says Doug Romm, a senior member of the technical staff of TI’s Standard Linear and Logic Product Group. “This has really paid off for us because most of our competition is using tin finishes.” Nickel-palladium-gold is also backward-compatible with exempt applications, like military/aerospace, some medical devices, and certain telecom applications. (While backward compatibility might seem to be an obvious goal as manufacturers begin releasing compliant parts, Schafer of Newark InOne believes that 5% to 10% of them have produced RoHS-complaint parts that do not perform exactly the same as leaded, or noncompliant, versions.)
If it’s inherently lead- and whisker-free, why doesn’t everyone go with nickel-palladium-gold? For one thing, says Ken Farrington, TI’s RoHS office manager, it’s an expensive transition. Also, he says, “We think a lot of our competitors weren’t willing to take that gamble with the RoHS deadline so close, so they had to go to matte tin. For them, it was mainly a logistics issue.”
But he says some TI competitors are making moves suggesting an eventual shift to nickel-palladium-gold. “You see that in some product portfolios,” he says. “We expect to see a slow migration to nickel-palladium-gold over the next several years.”
At this point, 98% of the lead-frame components Texas Instruments is shipping are nickel-palladium-gold. The remaining 2% are matte tin, but Romm says these components eventually will be switched over to nickel-palladium-gold. The holdouts are some subcontracted parts. Romm says that some of TI’s subcontractors are already producing nickel-palladium-gold components.
FORECASTING
RoHS compliance also has made forecasting and inventory control much more complicated. “Forecasting is difficult,” says Cindy Newell, senior manager of tactical marketing at Actel Corp., which supplies programmable logic products such as field-programmable gate arrays (FPGAs).
“Some of our customers have switched to lead-free devices without warning, or at different times. We have to have products in place to handle their demands. If we don’t, the lead times can be long, up to 10 to 13 weeks,” Newell says, adding that some of Actel’s assembly vendors have been working at 100% capacity. “So, you now have an unforecasted demand and their lead time pushes out.”
Then there’s the enforcement issue, which continues to baffle even the most knowledgeable RoHS sources in the industry. Despite murmurs of the publication of an EU RoHS Enforcement Guidance document, no one seems to know how the EU and its member states plan to enforce RoHS compliance.
“It’s not clear,” says Newell. “That’s why we’re seeing so many questionnaires, with questions ranging from, simply, ‘Are you compliant, yes or no,’ to very lengthy and complicated product surveys.”
HP’s Frey agrees. “It’s not very clear,” he says. “We know what we’ve been told, and we’ve made a fair number of guesses. But until the directive actually kicks in, and you start seeing the member countries doing their thing, it’s going to be very tough to tell what’s going to happen.”
Frey says it probably will vary from one EU country to another. “It’s going to be very challenging. Right now, everyone is making assumptions, and that’s the best you can do,” he notes.
UL’s Haataja’s has a more pointed view: “We’ll find out what constitutes compliance the first time there’s an enforcement action.”
With so little information and so much at stake, several industry manufacturing sources say requests for technical data have been picking up.
A CALL FOR HARMONY
Curiously, many industry companies, including the larger ones, are only now taking seriously the passage of recycling legislation in several states in the U.S. Most of these acts take dead aim at eliminating lead by focusing heavily on computers and monitors.
The Consumer Electronics Association (CEA) and the CTIA, the wireless association, both fear their members will have to deal with potentially 50 different laws. That's why these groups have been lobbying for a national solution. But there has been little movement in Congress to act on the several proposed bills, all of which seem stuck in some Congressional committee.
Along with other industry trade groups, both associations anticipate that additional, possibly even more stringent, environmental laws covering the industry will come out of the EU and other major market regions.
"This [RoHS] is just the starting point," says Actel's Newell. Unfortunately, that may be true for some companies that may or may not have made the July 1 deadline.
"If you're going to make the RoHS deadline, you better be making lead-free products today," says TI's Romm, "which means you should have been working on it a year ago."
See associated figure