Regulatory issues: Difference between revisions
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== Materials ==
Until recently, electronics manufacturers could use whatever materials they deemed necessary to make their products, and make them reliable and long
Most electronic solder has been made with the same formula since World War II (and before, in the case of some manufacturers like Kester). Scientists knew that a mixture of 63% tin and 37% lead was the
▲Until recently, electronics manufacturers could use whatever materials they deemed necessary to make their products, and make them reliable and long-lasting. Cadmium is a very toxic metal that was routinely used to plate electronic chassis, because it was corrosion-resistant and could be soldered to. But recent regulations in the US and Europe have banned cadmium in almost all products.
Lead does one thing for solder that is still poorly understood
▲Most electronic solder has been made with the same formula since World War II (and before, in the case of some manufacturers like Kester). Scientists knew that a mixture of 63% tin and 37% lead was the "eutectic mixture", meaning it had the lowest melting point. Since it's difficult to mass-produce solder to such a close standard, most solder manufacturers simply get it as close as possible and call it "60-40" solder. The difference is not critical (claims of some crackpots aside). Tin and lead are the least-costly metals that can be used in a solder, and give very reliable results when used properly, so the 60-40 mixture became the standard for electronics manufacturing. Solders made of bismuth can have a lower melting point, but are more costly and can have problems with reliable "wetting" of a wire or PC-board pad. Indium solders are excellent, but indium is extremely expensive. Solders carrying a high percentage of silver are also costly and are prone to oxidation. So the 60-40 lead-tin solder has been the most reliable, cost-effective mixture for more than 90 years.
▲Lead does one thing for solder that is still poorly understood today: it helps prevent a bizarre effect called "[http://www.guardian.co.uk/technology/2008/apr/03/research.engineering tin whiskering]". For some specialized applications, such as medical equipment or space-rated electronics, manufacturers will attempt to use a pure tin or tin-silver solder, to avoid the toxicity or other problems of lead. Whiskers can sometimes grow between electrical connections, shorting them out.
▲All well and fine--until 2006, when the EU promulgated the [http://en.wikipedia.org/wiki/Restriction_of_Hazardous_Substances_Directive RoHS] regulation. Along with banning cadmium plating, hexavalent chromium (also used to plate parts), and certain brominated chemicals that are used to make plastics more fire-resistant, it banned lead solder. Luckily there are a number of exemptions that any maker of modular synthesizers can take, thus avoiding RoHS problems when exporting to Europe. But the maker still has to include an RoHS exemption sheet with every shipment to an EU country. Companies that mass-produce consumer goods, like cellphones, personal computers, appliances and the like, have no recourse but to use lead-free solder.
There are attempts being made by legislators in other countries to outlaw the RoHS substances. The US Congress has considered it, though with no action to date. The State of California will probably outlaw lead solder soon, with other states likely to follow.
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==References==
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