Ken No I haven't read a paper, but these microcracks are frequently seen in our lab in failure analysis. They occur due to 3 reasons (as far as I know): - 2 Solidification fronts meeting each other and being already too cold to join. I believe that this is mainly a design problem. - Shrinking of the rest- eutectic between the Sn dendrites - Well I believe that a SnBiPb rest- eutectic is rare nowadays Best regards Guenter EMPA Swiss Federal Laboratories for Materials Testing and Research Centre for Reliability Guenter Grossmann, Senior Engineer 8600 Duebendorf Switzerland Phone: xx41 1 823 4279 Fax : xx41 1 823 4054 mail: [log in to unmask] --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------