Ivanoe Intermetallic Growth = Diffusion. Thus not a problem of cycling but of alloy, temperature and time. Formulas: Klein Wassink Thickness: In my opinion no minimum as long as there is an Intermetallic layer that indicates that alloying took place. Change in thickness from Sn63Pb37 to Sn62Pb36Ag2 = marginal, within the statistical spread of measurements. Best regards Guenter . EMPA Swiss Federal Institute for Materials Testing and Research Centre for Reliability Dipl. Eng. Guenter Grossmann 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 unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------