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(August 21, 2007) AUSTIN, Texas — Seiko Instruments Inc., subsidiary of SII NanoTechnology Inc., developed a reportedly simple and precise method to analyze 13 different types of metals — including silver and cadmium — in solder with one test, a technique it hopes to put to use in developing new lead-free solders that meet the EU's stringent RoHS directives, reports the Nikkei Business Daily.
Key to developing lead-free solders based on tin, silver, and copper is precise control over the relative ratios of the trace metal additives, and minimizing impurities leaching from the metal ores, such as cadmium, the paper notes. Current methods involve dissolving the solder in a mixture of hydrochloric and nitric acids, but large amounts of the former are needed to keep silver from precipitating out as silver chloride, which impacts the elemental analysis, Nikkei explains.
In SII's analysis method, solder is added to a solution of sulfuric and nitric acids to dissolve all the metals. A small amount of tartaric acid is then added, and the elements are analyzed using a special mass spectrometer, enabling measurement of concentrations down to <10 ppm, according to the firm.
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