David This translates to nothing because: - We don't know the temperature swing in your application. - 5 min. dwell time at -55 degC is as much as nothing, thus no strain is induced. - 10 degC / min is very fast below 20 degC and you are very likely to activate degradation mechanisms that do not occur in reality. Running a test - 0 / 120 degC - 4 degC / min up to 20 degC - 10 degC / min above 20 degC - dwell time of 5 min at 120 degC - dwell time 30 min at 0 degC would give in my opinion the possibility for a rough estimate of the lifetime in a realtime environment by Nfr = Nft ( dTt / dTr )exp1.7 Nfr = Number of cycles to failure reality Nft = Number of cycles to failure test dTr = Temperature swing reality dTt = Temperature swing test 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 unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet 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 ---------------------------------------------------------------------------------