Working toward a lead-free PC

Although PC and component makers are working toward removing hazardous substances such as mercury and lead from their products, that remains an uphill effort because of the diversity of manufacturers in the industry and the lack of proven alternatives, according to Terrence McManus, an Intel fellow and director of environmental health and safety (EHS) at the company. As a result, Intel is looking at 2006 as the "drop dead" date by which the healthy PC will become the norm.

Lead and other materials aren't considered a risk when computers, cell phones and other electronic gear are in operation, but rather when those devices end up in the trash. Environmentalists and others say that the metallic elements could seep from landfills into groundwater or waft from incinerators into the atmosphere, posing a threat to personal and environmental health. (Not everything ends up in the trash. For instance, manufacturers often melt down semiconductors for the traces of gold they contain, McManus said.)

But lead-free solders, used to glue microprocessors and other components to motherboards, tend to be more brittle than the lead-based solders now in service, McManus said. And even when lead-free alternatives turn out to be functional, component makers en masse have to adapt to the same solder and heat them to the right temperature to get the parts to adhere to the motherboard. If they don't, a component--and there can be hundreds on a motherboard--can dislodge.

"Changing the solder is huge--you've got to make sure everything works together," McManus said. "If you drop your cell phone, you may not just break the case. You may break the connections.

"What we want to avoid is having to have two processes, leaded and unleaded," he added.

Progress, though, is under way. Next year, Intel will use a "flip chip" package for its microprocessors that comes with lead-free "bumps," the metallic connectors that let electricity flow into the processor, for chips made on the 90-nanometer process. Current packages use bumps made from a tin-lead alloy.

Sony Electronics, meanwhile, has a factory in Mexico that is using lead-free solder, and the company is offering products manufactured that way.

"It's still an expensive, time-consuming implementation, and the alternatives are not acceptable in some areas," Mark Small, the company's vice president of environmental affairs, said earlier this year. Still, he said, "the use of lead in solder has limited life expectancy. It will most likely be phased out in next five years."

Manufacturers are also looking at lead-free alternatives for other types of connectors for different components. Tin-silver-copper is emerging as the main alternative to replace lead for solder paste and solder balls. Matte-tin is an alternative for lead-frame finish materials, the needlelike inserts found on the bottom of capacitors and other components. The main problem with matte-tin, however, is tin "whiskers," extraneous shavings that can scramble signals.

Intel also has reduced some of the environmental hazards with a shift to manufacturing chips on 300-millimeter wafers. Per square inch, the 300-millimeter wafers mean a 48 percent reduction in volatile organic compounds, compared with older 200-millimeter wafers.

"We've integrated the EHS piece so it is part of the development process. It is not an appendage," McManus said.

Intel's efforts, however, address only part of the lead problem. The bulk of that metal is found in CRT (cathode-ray tube) monitors of desktop PCs and television sets, as much as six pounds by some estimates, and two pounds according to McManus' statistics. By comparison, motherboards and other components contain only a few grams of lead.

The threat of pollution from electronic devices has goaded legislators into action at both the state and federal levels.