HERNDON, VA  — iNEMI’s High-Reliability RoHS Task Force has published process and reliability guidelines for high-reliability electronics that may include both SnPb and Pb-free parts. Reliability concerns arise due to the differences in processing temperatures and materials.
 
RoHS5 modules (5 of 6 RoHS materials) are products that are RoHS-compliant, but contain Pb (under an applicable RoHS exemption). RoHS6 modules (6 of 6 RoHS materials) are soldered with Pb-free solder and are fully RoHS-compliant and Pb-free.
 
With current RoHS exemptions for high-reliability electronics, it is possible for assemblies to contain Pb and still be RoHS-compliant. Manufacturers taking the Pb exemption will continue to require SnPb-compatible components for their products, and may also use subassemblies, such as hard disk drives and power modules, that may or may not be Pb-free. 
 
Thilo Sack, principal engineer, corporate technology, for Celestica and co-chair of the iNEMI High-Reliability RoHS Task Force, noted, “If RoHS6 subassemblies are to be used in RoHS5 products, the subassemblies should be thoroughly qualified to ensure that they will meet the higher reliability requirements of the RoHS5 products. Furthermore, in some cases solders and processes should not be mixed. For example, only BGAs with SnPb solder balls should be used in a SnPb assembly process, and only SAC solder balls in a SAC process.”
 
The task force recommends that Pb-free Sn finishes on leaded and discrete components only be used when these finishes (1) include suitable tin whisker mitigation practices, per IPC/JEDEC JP002, and (2) have passed Class 2 level tin whisker acceptance testing requirements, per JESD-201. For subassembly modules meeting RoHS5 or RoHS6 requirements, plated leads or pins that will be attached to the PCB should be backward compatible with SnPb assembly processes.
 
The complete guidelines can be downloaded here:
http://thor.inemi.org/webdownload/projects/ese/High-Reliability_RoHS/High_Rel_position_061206.pdf
 
The task force consists of OEMs and EMS providers with long service life products and high-reliability requirements, including:
Agilent Technologies, Alcatel, Cisco Systems, Celestica, Delphi Electronics & Safety, HP, Intel, Jabil, Lucent, Plexus, Sanmina-SCI and Sun Microsystems.