The mercury in one compact fluorescent lightbulb may not pose much of a health hazard, but when all electronic parts are taken as a whole across the globe, the level of hazardous materials is monumental. But now, a directive legislated by the European Union known as “Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment” (RoHS) has mandated that manufacturers restrict the use of lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers in such equipment by July 1, 2006.With the clock counting down, manufacturers worldwide are focused on bringing components into compliance. And even though the directive was initiated in Europe, any manufacturer in — or hoping to enter — the global market will have to comply. So far, 15 of the 25 member states of the European Union have passed either RoHS or the complementary directive on waste electrical and electronic equipment (WEEE); 10 have enacted both directives. Japan has been working on a similar reduction in hazardous substances since the 1990s and already has in place very strict waste and recycling laws. China is working on comparable, but possibly even more restrictive, legislation. And in the US, where similar legislation must be passed state by state, California and Maine are the first on the books, with at least five other states pending.Gary Nevison, head of product market strategy at Premier Farnell in Leeds, UK, and chairman of the UK-based Association of Franchised Distributors of Electronic Components, said that manufacturers have taken mixed approaches to compliance. “If all our customers required compliant products tomorrow, there wouldn’t be enough to go around.”Manufacturers have to supply compliant parts to end users before they, in turn, can begin to manufacture compliant products. In the meantime, distributors and retailers may have stockpiles of noncompliant products in the warehouse. For this reason, RoHS allows the sale of noncompliant stock manufactured prior to July 2006, and noncompliant spare parts to be used to maintain and repair older equipment.Products affected by the legislation include those designed for use with a voltage rating not exceeding 1000 VAC or 1500 VDC. However, an amendment to RoHS being considered would set maximum concentration values for the restricted substances and would state that the materials to be tested are “each homogeneous material” used in a product. This would greatly expand the number of affected products, depending on the number of homogeneous materials in the final product. Nevison noted that typical semiconductors would have about six homogeneous materials, so that, although each alone may not amount to much, the sum total could push the final product over the limit.Guidelines of the directive suggest that the key to success is how well a manufacturer knows a supplier. If an end user trusts the supplier, then he or she can be fairly confident that the parts are compliant. In some cases, manufacturers will seek new suppliers. They may go to a source from Asia — where compliant products may be available sooner than their usual source — but if they don’t know them, it may be wise, Nevison suggests, to have checks done at one of the many labs testing for RoHS compliance.Another challenge to manufacturers and end users is the solder that binds individual parts together. According to Nevison, lead-free solder is a big issue; for example, it has a higher melting point, which can result in problems on densely populated printed circuit boards.At Rochester MicroSystems Inc., an electronic design services firm in Rochester, N.Y., President Mark Corio has seen the lead-free solder issue firsthand: One customer had a part that the assemblers didn’t know used lead-free solder. Corio said that assembling the prototype was a nightmare because some of the solder was lead-free while the rest wasn’t.Then there may be reliability issues, because alternatives to lead-based solder may not be as durable. Mary Knighton, CEO of Wavelength Electronics Inc. in Bozeman, Mont., took to heart a warning from David Suraski of Montreal-based AIM (in a “webinar” sponsored by SMT magazine) that using lead-free solder on parts that are not lead-free can cause field failures. Her company intends to convert to lead-free parts prior to implementing the process changes needed to accommodate this solder.One change, Knighton noted, is that Wavelength has had to plumb its soldering irons with fume extractors because the fumes from lead-free solder are more toxic.Another challenge that manufacturers face because of RoHS is how to number parts to differentiate compliant vs. noncompliant ones. Some manufacturers don’t want to change because new numbering will mean changing bills of materials, which can be time-consuming for a large operation. Others want to change for traceability purposes, assigning new part numbers to indicate compliance. Corio, who has spoken with companies that have more than 100,000 parts, estimates that the paperwork required to assign all new numbers would take tens of decades of man-hours. Again, this is an area that needs to be ironed out, but one that undoubtedly will result in additional costs to manufacturers.Although RoHS requires only self-declaration of compliance and not official lab testing, noncompliance is not an option — and failure to comply can come at a high price. Nevison acknowledged that it’s uncertain who is going to police RoHS in the UK, one of several issues still to be resolved. Undoubtedly, capital and operating expenses, as well as research and development costs, will trickle down to consumers. But the overall benefit to manufacturers who embrace the legislation could be market share. Coupled with the complementary WEEE directive, the overall benefit to everyone is the environmental impact. Nevison said that, across Europe, there are 85 million electrical waste products, amounting to 6 million tons. Reducing the level of harmful materials in those products will decrease the levels of toxins in landfills.LED Suppliers Leap RoHS HurdlesHigh-brightness LEDs continue to gain momentum as light sources because of efficiency improvements and cost-reduction trends associated with semiconductor devices. Early adopters in such markets as signage and transportation have capitalized on LEDs’ advantages regarding improved lifetime, reduced warranty-replacement costs, instantaneous emission and vivid saturated colors. Although substantial challenges — such as thermal management, color consistency of white emitters and the thirst for even higher efficiencies — will keep LEDs out of many general lighting applications, a new wave of environmental consciousness and associated legislation is expected to assist the proliferation of LED-based solutions.A major hurdle for end users, service providers and component suppliers alike is the European Union’s “Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment” directive (RoHS). Although RoHS exempts certain military and telecommunications systems until 2010, the availability of proven alternatives, coupled with the reduction of noncompliant parts, will push everyone affected to comply before then.Alternatives to toxinsIn the semiconductor industry, it is the packages that must meet RoHS regulations rather than the chips themselves, which traditionally have relied on restricted elements for electrical and thermal interconnection and for encapsulation-material additives to meet flammability requirements. For example, alternatives to conventional brominated phenolics, such as polybrominated diphenyl ethers, are employed as flame-retardants in epoxy-based molding compounds, and there also are replacements for the compounds used in mainstay FR-4 (flame-retardant) printed-circuit-board laminates.A key concern is replacing the traditional tin and lead alloys used to solder components to printed-circuit-board substrates. Sn/Pb alloys have been used for 50 years because they provide reliable, high-strength, low-resistance, relatively low temperature and processible solutions for both a standard ohmic contact and a high-integrity interconnect contact of semiconductor and electronic components. But now, a new generation of lead finishes and soldering materials is emerging to replace them.LED advantageUnlike conventional semiconductors, LED packaging does not use flame retardants within the emissive plastic window because they compromise the optical transmission properties needed to extract light from the package. Furthermore, high-temperature (>260 °C), lead-based, internal soldering alloys are exempt from the directive. Hence, only the lead terminations are subject to the directive, and many termination options are already being used in production devices.Filament-based light sources and fluorescent tubes are exempt from any directives, but such lighting solutions will come under fire as LEDs and other clean-light sources become mainstream. The benefits of LEDs include low power, less radiated heat, longer lifetime, reduced warranty-replacement costs and compact size. These benefits provide incentives to manufacturers to develop lead-free products, even without RoHS.Although end users will not realize immediate value, the expectation is that the high recycling costs for non-environmentally friendly systems will trickle down to consumers. As a result, suppliers of consumer products are racing RoHS-compliant systems to market to gain a competitive edge.Depending upon the source, global RoHS-compliant semiconductor shipments represent 15 to 20 percent of demand. Technical problems from the processing and device perspectives do not represent a formidable challenge. Key concerns for implementation include timely product availability, logistics, order entry, compliance and the elimination of noncompliant devices. When these are achieved, suppliers will have a leg up on their competition. Additionally, one advantage to end users is the knowledge that high-brightness LEDs for illumination applications are deemed environmentally friendly.