Jason, If the failed mechanism is corrosion of a glass diode, you may need to precondition your sample before you subject it to HAST testing. Preconditioning would most likely consist of temperature cycling or power cycling, though care must be taken not to overstress the part beyond the stresses expected in its operating environment. In addition, during HAST avoid extremely high relative humidities (i.e., 95%), as you will often get moisture condensation, which may not be an actual condition in the field. Best Regards Craig Dr. Craig Hillman CALCE Electronic Products and Systems Consortium University of Maryland College Park, MD 20742 (301)-405-5316 [log in to unmask] ############################################################## 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 ##############################################################