Stephen I want to thank you for your "spare time" research activities. They are saving me a lot of time. I have read the NASA report and I want to make a few comments about it. 1. The information contained in this report is very “dated”. The newest data is from 1992. 2. Most of the conclusions are based on testing of DIP PEM packaging for TH assemblies. 3. No airborne contamination loading was used for any testing (except for a limited salt fog test). The use of this report to justify the acceptability of PEMS for use in high reliability assemblies is a dangerous “Leap of Faith”. PEMS currently used for assemblies bare virtually no resemblance to the components evaluated in this report. The changes in size, materials, operational voltage levels, frequencies, and signal strengths have a combined effect of lowering the amount of moisture plus contamination levels needed to disrupt circuitry operation. This report is only of limited value for the component types tested. The lack of airborne contamination loading during testing means they are only useful for determining the “as built” cleanliness, purity of materials, and processes used in the manufacturing of components. It does not provide any useful information as to the durability of components when exposed to real world “harsh environments”. Salt fog testing does not correlate to any real world loading conditions and is primarily used to detect “infant mortality” failure modes. With the onset of “performance based contractual requirements”, the lack of real world contamination load testing of circuitry causes very ugly situations to develop. It is no longer very useful to evaluate PEMS independently of the substrates/laminates to which they are attached. The changes in the design and packaging of PEMS are reflected by corresponding changes in substrates. This will cause the whole assembly to become more sensitive to moisture/temperature/contamination combinations. This report is very useful in several respects. It demonstrates the dangers of transferring legacy test data from obsolete hardware to current production equipment. It can be very misleading. It also highlights the time lag issue, i.e. by the time testing protocols are agreed to, testing is done, and evaluation is completed there is a very good chance the the component is obsolete! D. A. Douthit ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################