David's original question was also posted on the lead-free forum.  Werner gave this response (copied here for info of those not on the other forum.  jack

There are 2 IPC documents:  IPC-SM-785 "Guidelines for Accelerated
Reliability Testing of Surface Mount Solder Attachments," and IPC-9701
"Performance Test Methods and Qualification Requirements for Surface Mount
Solder Attachments. "
IPC-9701 is brand-new and the guidelines are valid; there is no real need to
change them for lead-free solders. There is no distinction in either document
about Classes 1, 2, or 3, nor should there be.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

>>> [log in to unmask] 06/27/01 10:08AM >>>
David,

There are no thermal-cycling guidelines for IPC Class II assemblies. Thermal
cycling should be dependent upon expected usage environment. If your
assemblies will be powered on once and used in a climate-controlled
environment, why thermal cycle? If they are going to be used under the hood
of a car engine, appropriate thermal cycling might require months of
testing. And everything in between.......

Craig


  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]]On Behalf Of David Suraski
  Sent: Tuesday, June 26, 2001 3:46 PM
  To: [log in to unmask] 
  Subject: [TN] thermal-cycling guidelines


  Could anyone advise the recommended thermal-cycling guidelines for IPC
Class II assemblies, or point me in the direction of the appropriate spec?
Will these be revised for lead-free assemblies?

  Regards,
  David

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