I do not discount low temperature ranges--what I discount is the combination of low and high temperatures in the same test cycles. This confounds a number of different damage mechanisms. Sure, cycling assemblies from -55 (or -65) to +125 (or +150) C will give you failures fast, but so does dropping them from the Empire State building. What do these cycles mean for your product that never sees any cycles even remotely close to the test cycles? It is NOT accelerated reliability testing, because you do NOT accelerate a damage mechanism that is dominant for your product, but create a different dominant damage mechanism(s) and their interactions. This has clearly been shown by Roger Wild, IBM, many years ago and that is the reason that most new military contracts no longer put those cycle extremes as requirements. Just because something is popular (actually a hold-over from the old military hay-days and people do not like change) does not make it technically correct. If the customer requires these cycles you are stuck. You had better design your electronics to meet these requirements, which in most cases means that these assemblies are less reliable in the field than they could be if the requirement were more closely associated with actual use conditions. Managers sure like these tests, because they take much less time than properly designed accelerated reliability tests. But they are like 'security blankets,' they sooth the mind but are no real protection. It is my opinion, that if you can not do proper accelerated testing, you are better of not to do any testing at all--saves more money too. PS: What is "Engelmaier's Curve"? I don't know of any other Engelmaier in this industry, but I sure have never heard of "Engelmaier's Curve" Werner Engelmaier Engelmaier Associates, Inc. Electronic Packaging, Interconnection and Reliability Consulting 23 Gunther Street Mendham, NJ 07945 USA Phone & Fax: 201-543-2747 E-mail: [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************