Impact of the ROHS directive on high-performance electronic systems

The European Union enacted legislation, the ROHS Directive, that bans the use of lead (Pb) and several other substances in electronic products commencing July 1, 2006. The legislation recognized that in some situations no viable alternative Pb-free substitute materials are known at this time, and so provided exemptions for those cases. It was also recognized that certain electronic products, specifically servers, storage and storage array systems, network infrastructure equipment and network management for telecommunication equipment referred to as high-performance electronic products, perform tasks so important to modern society that their operational integrity had to be maintained. The introduction of new and unproven materials posed a significant potential reliability risk. Accordingly, the European Commission (EC) granted an exemption permitting the continued use of Pb in solders, independent of concentration, for high-performance (H-P) equipment applications. This exemption was primarily aimed at assuring that the reliability of solder joints, particularly flip-chip solder joints is preserved. Flip-chip solder joints experience the most severe operating conditions in comparison to other applications that utilize Pb in electronic equipment. This paper briefly describes the solder-exempted H-P electronic products, their capabilities, and some typical tasks they perform. Also discussed are the major attributes that differentiate H-P electronic equipment from consumer electronics, particularly in relation to their operational and reliability requirements. Interestingly, other than the special solder exemption accorded to H-P electronic equipment, these products must meet all the other requirements for ROHS compliancy. The EC was aware that issues would surface after the legislation was enacted, so it created the Technical Advisory Committee (TAC) to review industry-generated requests for exemptions. The paper discusses three exemption requests granted by the EC that are particularly relevant to H-P electronic products. The exemptions allow the continued use of lead-bearing solder materials.