The Emperor's New Lead-Free Clothes
John Baliga, Associate Editor -- Semiconductor International, 9/1/2000
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It's not an easy thing for people to come out and say, because the demand for lead-free is out there, and companies cannot afford to turn their backs on the lead-free market. I find that the private opinions of those who stand to gain, as well as those who stand to lose, generally agree that the environmental motivation is not valid. And, of course, everybody can plainly see the benefits of lead-free, just as everyone in the famous story could plainly see how beautiful the emperor's new clothes were.
First, the electronics industry uses about half a percent of the lead consumed in the world. If lead is as bad as people think, there would be better places to focus environmentally conscious efforts.
The largest environmental concern from the electronics industry, by far, is not throwing cellular phones into landfills, but dumping chemicals. Dumping of used plating chemicals, for example, puts harmful chemicals straight into the ground in a form that can readily harm the ground water. This is reprehensible, but not specific to the use of lead. Any used plating bath or similar chemical would do great harm, lead-based or not.
If you put large amounts of lead in vats of solvent, and placed those vats in landfills, you would be threatening the surounding ground water. We recycle car batteries now, so that doesn't happen much anymore.
If electronic devices, like cellular phones, are dumped in landfills instead of being recycled, nothing much happens. With the underfills and conformal coatings used for flip-chip and surface mount technologies, respectively, the small amount of lead in those devices is well concealed. Some sort of solvent would have to eat through all that protection and transform the lead into a form that is soluble in water. The lead paint from torn-down buildings would pose much more of a threat.
If we combine the lead-free effort with another "environmentally conscious" effort, halogen-free circuit boards, we have what one industry expert calls "our own version of the perfect storm." The likely replacement for bromating boards is to coat them with phosphorus. These boards have a lower glass transition temperature, so they are more likely to melt. When they do, phosgene gas is emitted.
Let's see: higher melting solders, lower melting boards and phosgene. There may be a perfectly safe way of making lead-free work with halogen-free, but I prefer to watch from a good distance. I haven't even addressed the risks involved with handling phosphorus-coated materials.
There are benefits to be had from the work that has been done. For example, we could extend the hierarchy of melting temperatures to allow more levels of solder connections. We don't need to jump on the lead-free bandwagon to use the technology that has been developed.
If we want to be an environmentally conscious industry, we can continue to reduce emissions, develop processes that reduce or eliminate harsh chemicals and hold offenders of current laws responsible. Lead-free implementation schedules have been pushed out, so maybe lawmakers are figuring out that lead in electronics is not so horrible. I'd rather we not get the lead out just because it's stylish.
