Determination of Lead (Pb) concentration level in solder finished product using Laser Induced Breakdown Spectroscopy (LIBS)

In February, 2003, the European Union adopted the RoHS Directive 2002/95/EC (Restriction on Hazardous Substances). The directive sets limits on the concentration of six environmentally toxic substances in various electronic products and electrical equipment. These six substances include Lead (Pb), Mercury (Hg), Cadmium (Cd), Hexavalent Chromium (Cr+6), Polybrominated biphenyles (PBB) and Polybrominated diphenyles ether (PBDE). One of the RoHS regulated substances, Lead (Pb), is linked to nerve, blood and brain disorders in humans, especially in young children. Currently, the RoHS concentration limit for Pb stands at 1000 ppm. Since some manufacturers are producing products with and without lead at a single manufacturing facility, it stands to reasons that a fast, sensitive, in-line analytical technique is necessary to monitor lead concentration levels. Such a technique would ensure compliance with ROHS regulations for solder finished products, while also checking the consistency of the manufacturing process. This paper introduces an innovative, alternative method of monitoring the Lead (Pb) concentration levels in solder finished products based on Laser Induced Breakdown Spectroscopy (LIBS). An extensive experimental investigation has been performed to compare the LIBS analytical results with other analytical techniques that are available for Pb concentration analysis, namely ICP-OES, AAS, EDXRF, micro-EDXRF and LA-ICP-MS. While providing accuracy and performance comparable to ICP-OES (the currently accepted industry standard) LIBS provides additional advantages such as rapid analysis and the elimination of complex sample preparation involving acid dissolution.