In a message dated 08/02/2003 0:50:34, [log in to unmask] writes: >By now I have seen quite a bit of ATC presentations for Lead Free and I am >a bit surprised that this is the first time I have read about a soak or >dwell time at each temperature extreme. Most have reported that they just >go up and then back down in temperature. 30minutes up and 30 minutes down, >thus 24 cycles a day across the range they have selected seems quite common. >Any comments?? >Have you also seen this type ATC procedure? Hi Dave, Yes, unfortunately I have seen them--and it's a pity. These data are worse than useless--they are misleading. But that comes from people doing things without understanding them, and from people being pushed to produce data fast--nevermind that they are meaningless. As an example of this, just look in the Circuit Assembly magazine, July 2003, page 25, in "The Cost of Going Green," [we all know by now the going lead-free is anything but 'Going Green'], where the author Alan Rae, cookson Electronics, Inc., states under the heading "What is the reliability compared to eutectic solder?" We tested reliabilty--air-to-air, liquid-to-liquid--between 550°C and 1250°C [I would think he meant -55 and 125°C]. We found no major difference between the alloys and surface finishes, but we did find that large resistor components (1206) failed frequently due to joint cracking under thermal stress." Using thermal shock tests with no hold times is put forth as proof that LF-solders are not different than Sn/Pb solders. Regards, Werner Engelmaier --------------------------------------------------- Technet Mail List provided as a free 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------