This doesn't answer you questions directly but still may be of some use in your decision. IPC SM-785, sections 3.4.3 & 7.3.3 goes into these issues. They briefly present the differences in stresses applied by each (TS vs. TC) and summarize stating that TS for SM is only recommended if the TS conditions are likely to be encountered in actual field use by the product. IPC 9701 goes into the details of selecting the test parameters and may be of some use to you. Rich Kraszewski Advanced Manufacturing Engineer - KEDS Phone: 260.925.8919 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Marsico, James Sent: Tuesday, June 22, 2004 1:27 PM To: [log in to unmask] Subject: [TN] Shock vs. Cycling Good day Technet: I will be starting an evaluation shortly to determine the reliability of soldering RF components (no compliant leads, flat leads coming right out of the bottom of the package) directly to the PWB. (In the past we always soldered ribbon jumper leads from the component leads down to the PWB to ensure strain relief.) We intend to subject the test hardware to thermal excursions typical of the actual hardware environment. My question is which, if any, is the worst case with regard to longevity of the solder joints, thermal shock, with virtually no ramp between temperature extremes, or thermal cycling, with a ramp of, lets say, a minimum of 5 degrees C per minute? Opinions are OK, but if you have technical justification for your answer, it will be appreciated. Thanks in advance, Jim Marsico Senior Engineer Production Engineering EDO Electronics Systems Group [log in to unmask] <mailto:[log in to unmask]> 631-595-5879 --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------