Hi Poh, Yes, studies like this have been done. Basically what kills the solder joints on Alloy 42 TSOPs is the large global CTE-mismatch with FR-4, which depending on the design details can be larger than a factor of 5 than the CTE-mismatch between copper TSOPs and FR-4. The local CTE-mismatch between the Alloy 42 and the solder itself also does not help. Using Appendix A of IPC-D-279, 'Design Guidelines for Reliable Surface Mount Technology Printed Board Assemblies', you can determine the particular difference for your situation and the resulting difference in cyclic lives, which can be as large as a factor of 50. Of course, you can also engage my services to estimate the reliability of your solder attachments on your product for your application. Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 23 Gunther Street In December: Jasmine Run Mendham, NJ 07945 Ormond Beach, FL 32174 USA Phone & Fax: 973-543-2747 Phone: 904-437-8747, Fax: 904-437-8737 E-mail: [log in to unmask] ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################