Guenter: Should the rate of temperature decrease be the same as the rate of temperature increase that you quote? Dave Fish Guenter Grossmann wrote: > 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 > --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------