Impact of the ROHS directive on high-performance electronic systems

摘要: There are important logistical and technological issues that confront the electronics industry as a result of implementing lead (Pb)-free technology to comply with European Union’s (EU) ROHS Directive effective July 1, 2006. This paper focuses on matters pose greatest potential risk reliability so-called high-performance (H-P) systems (i.e., servers, storage, network infrastructure/telecommunication systems). The Commission (EC) specifically granted special use (Pb) in solder exemptions, independent concentration, for applications H-P systems. intent was preserve joints, particularly flip-chip joints. perform mission-critical operations, so it is imperative they maintain continuous flawless operation over their lifetime. expected experience virtually no downtime due system failures. discusses several major impede implementation Pb-free solders topics discussed include compatibility risks mixed joints component availability problems. effects microstructural factors, such presence Ag3Sn platelets, ways eliminate them described. Also stress-test parameters have thermal-fatigue life compared eutectic Sn–Pb. Another issue involves effect tin’s body-center tetragonal (BCT) crystal structure has solder-joint reliability, complete loss structural integrity associated an allotropic phase transformation at 13.2°C, referred tin pest. Yet another consideration tendency pure or tin-rich finishes grow “whiskers” can cause electrical shorts other Finally, notes electromigration failures Pb-free, Based current status discussed, appears likely exemption allowing will need be extended by EC when scheduled review 2008, perhaps well into future.