Kuan As Werner already mentioned, the metallurgy of your solder joint will change significant during the annealing. However, it depends on the conditions of use whether this changes ( Thicker intermetallics, enhanced Pb concentration at the interfaces, growth of Pb phases, secondary segregation in the bulk etc. ) are of significance for the reliability of your assembly. As much as I remember, Werner, didn't you do some work on tested joints with and without annealing in order to show that annealing ahead of thermal cycling tests is important? Best regards Guenter Guenter Grossmann Swiss Federal Institute for Materials Testing and Research EMPA Centre for Reliability 8600 Duebendorf Switzerland Phone: xx41 1 823 4279 Fax : xx41 1823 4054 mail: [log in to unmask] ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8d ############################################################## 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. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################