Hans, Below are some comments on the issues you raised. In a message dated 97-03-21 11:06:58 EST, you write: << I'm Investigating mechanical failures (cracking) of solder joint for J-leaded surface mounted components (SOJ). The primary casue is due to the CTE mismatch between the PWB and the cermic SOJ. COMMENT: Local CTE mismatch between solder and the lead (especially when the leadframe is Alloy42 or Kovar), and too stiff of a lead may also be contributing factors. Any sources of information for the following? Stress/Strain relationship of eutectic solder (63 Sn, 37 Pb) COMMENT: The International Tin Research Institute (UK) has publications on the subject. You may be able to locate ITRI on the Web, or by contacting Bill Hampshire (Hampshire Technical Services) in Columbus, Ohio. In general, these stress/strain relationships are isothermal (+ fixed strain rate). While they give useful information on the mechanical strength of solder, they do no infer anything about fatigue. Cyclic creep-fatigue is what matters most for SMT reliability. Any alternatives for mounting these J-leaded devices using the same footprint? Any similar experiences to this type of problem and how was it solved? COMMENT: two possible approaches (each with its own implications) are: 1) use a component with more compliant leads. 2) use a substrate with lower CTE. On rare occasions, similar problems were resolved by switching from standard Sn-Pb to an alloy with a higher fatigue resistance (a more daring approach because material compatibility issues may have to be worked out). >> Attachment reliability is application-dependent and there are many variables involved (board, component, lead geometry + material properties). I can't be more specific without seeing your package outline (size + lead geometry) but I hope this helps. Jean-Paul ________________________________________________________________ Jean-Paul Clech EPSI Inc., P. O. Box 1522, Montclair, NJ 07042 - USA tel: +1 (201)746-3796 fax: + 1 (201)655-0815 Home page: <A HREF="http://members.aol.com/Epsiinc1/index.html">http://members .aol.com/Epsiinc1/index.html</A> - click on the above or copy: http://members.aol.com/Epsiinc1/index.html __________________________________________________________________ *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************