Johnathan, There is a great body of knowledge about solder joint reliability at both mild thermal cycle and harsh thermal cycle at the JCAA-JGPP report location under NASA TEERM: http://teerm.nasa.gov/LeadFreeSolderTestingForHighReliability_Proj1.htm The project 2 results report is at http://teerm.nasa.gov/nasa_dodleadfreeelectronics_proj2.htm I am puzzled why you think you cannot pass 1000 cycles at a delta of 100 degrees C. In both studies, but lead based and Pb-free solders passed far more cycles than that. In fact, the Pb-free boards from test 2 are probably still being cycled at Boeing in Seattle. In harsh cycle, lead-based solders perform best, in mild (100C) cycles, Pb-free solders perform best. Denny Fritz -----Original Message----- From: jonathan noquil <[log in to unmask]> To: TechNet <[log in to unmask]> Sent: Mon, Apr 2, 2012 12:55 pm Subject: [TN] how to pass solder joint reliability of a 3.2 mm board (16 layers) for QFN packae Hi All Need some suggestions on how to handle solderjoint issue (How to tweak to ass TMCL1000 cycles- 0 to 100C) on QFN packages ( 5 x 6 x 1.0 mm with 8 ins). inish is Pure Sn oard is 16 layers 3.2 mm, HASL finish. Does someone had an experience to share? thanks _____________________________________________________________________ his email has been scanned by the Symantec Email Security.cloud service. or more information please contact helpdesk at x2960 or [log in to unmask] _____________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________