Most design engineers don't give much thought to solder, but it's at the heart of one of the biggest transitions the electronics industry has made in decades. It will be illegal to sell gear with lead-based solder in Europe after July 1, 2006, and that's causing huge headaches throughout the industry.
"Immense, complex, and confusing" are among the polite terms being used to describe the transition. Issues causing engineers to burn the midnight oil range from supply chain problems, such as numbering parts, to reliability issues surrounding the high temperatures needed to produce boards using lead-free solders. The shift from venerable lead-based solder is driven by Europe's Restriction of Hazardous Substances law, which bans lead and other materials deemed harmful to the environment.
One key reason for concern is that lead-free solders melt at 217-221C, much higher than the 183C needed for conventional tin-lead solder. That brings reliability concerns beyond those normally associated with new materials. At the same time, the shift is prompting huge changes in the supply chain as companies debate the importance of having different part numbers for conventional parts and lead-free versions.
The changeover won't be cheap. "I think redesign and manufacturing changes will be about 2 percent of the cost of goods sold for the average OEM to get goods compliant," says Pamela Gordon, president of Technology Forecasters of Alameda, CA (http://rbi.ims.ca/3852-524). This is a non-recurring cost, she notes.
The actual job for design engineers who lay out boards will be impacted only slightly. But most will have to spend hours working with component vendors and manufacturing engineers to determine how to make sure reliability and manufacturability are not impacted.
Electronics companies manufacture for global markets, so most are converting their entire product lines and manufacturing operations to lead-free operations. Though some companies don't sell to Europe and some manufacturers have exemptions beyond 2006, they will be impacted nearly as much as companies that sell globally.
"One of many questions we have is whether a particular part number will still be available once a company goes lead free. They may discontinue the lead solder version," says Jim Smith, senior vice president of operations at Avnet Electronic Marketing Americas in Phoenix (http://rbi.ims.ca/3852-525).
Part numbers crucial
Part numbering is one of the central issues facing everyone in the supply chain. Avnet wants to see new part numbers so there's no way that components can be accidentally intermixed. The preference of Solectron Corp. is equally clear. "We want new part numbers," says Kim Hyland, director of process integration at the Milpitas, CA-based contract manufacturer (http://rbi.ims.ca/3852-526).
Some vendors are complying, but connector makers, among others, say it's too difficult to double a parts catalog that's already in the thousands. "Connector makers are our biggest nemesis on this," Hyland says.
Some chipmakers are also avoiding renumbering. Texas Instruments of Dallas won't revise part numbers except for customers who request new numbers (http://rbi.ims.ca/3852-527). However, TI won't make lead solder versions once a line is shifted to nickel-plated gold leads, says Mel Jordan, TI Semiconductor's lead-free and green program manager. TI has converted about 70 percent of its chips to lead-free and expects to be at about 95 percent by year's end, he adds.
It's not only the chance of intermixing lead and lead-free components that concerns quality control and manufacturing engineers. There are a number of different alloys, each with specific positive and negative attributes. Some of them require different processing techniques, and parts can be damaged if they go through the wrong solder process.
The National Electronics Manufacturing Initiative (NEMI), a Herndon, VA consortium that has four separate task forces working on lead-free issues, just completed a guideline for identifying electronic components and board assemblies during the transition to lead-free. "It's a small E with numbers 1-7 that can be on components or boards telling people what solder paste is being used," says Vivek Gupta, the Intel Corp. manager who chaired the NEMI project, done in conjunction with JEDEC (http://rbi.ims.ca/3852-528).
The seven categories of solder have different melting temperatures, ranging from 150C for Indium to 217C for tin silver copper. "There are compatibility issues if you use bismuth solder with lead and if you use bismuth in the system, people doing recycling need to use special processes," Gupta says.
These compatiblity issues can arise when one or two parts have lead, which can still be used so long as there's less than 0.1 percent lead on a board. While some lead-free solders can be used with parts that have traces of lead, that's taboo with others. "If you go with tin bismuth solder, you have to be sure there's no lead on the board," says Mark Newston, manager of environmental affairs at Dell Inc. (http://rbi.ims.ca/3852-529).
Fewer solder types possible
There's some hope that the number of solders will decrease before long. The Solder Value Council, made up of solder producers from around the globe, is currently running the alternatives through a number of tests, which should be complete late this year. "We are trying to come up with data that would support going to one or two alloys," says Roger Savage, vice chairman of the council, who is also president of Kester, a Des Plaines, IL solder maker owned by Northrop Grumman (http://rbi.3852-530).
While much of the industry focus is on eliminating lead, there are other materials in IC packages that are also being banned. Mercury, cadmium, halogen, and chromium are also being phased out.
Many system and subsystem vendors are sending out questionnaires asking about lead and those materials. Component makers are struggling to fill out request forms that come in a variety of formats, often asking for data about scores of products. "There's a tremendous burden on the supply chain. There's a lot of work by committees developing a standardized reporting format," says Fern Abrams, director of environmental policies for the IPC, a Northbrook, IL circuit board association that has been studying lead-free solder for years (http://rbi.ims.ca/3852-502).
Managing the huge volumes of data will be a time-consuming task for the next few years, most predict. "We get process change notices for die shrinks and other things, but now every one of our parts has changes that we must pay attention to," Hyland says.
|Check out the links below for more info
|NEMI, an industry consortium of electronic companies, is hosting a series of lead-free initiatives and publishes regular updates: http://rbi.ims.ca/3852-503
||The IPC runs an entire site devoted to the lead free solder issue: http://rbi.ims.ca/3852-504