Hi Martin - In addition to the references that Werner mentioned you might take a look at the book "Solder Mechanics: A State of the Art Assessment",Frear/Jones/Kinsman, ISBN 0-87339-166-7. Chapter 2 contain an excellent compendium of references that may be helpful in investigating Cu-Ni-Sn/Pb solder bonds vs. Cu-Sn/Pb solder bonds. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Re: ASS. Reliability of solder bonds Author: [log in to unmask] at ccmgw1 Date: 6/9/97 9:01 AM Hi Martin, To my knowledge there are no direct studies on the reliability differences of Cu-Ni-Sn/Pb solder bonds vs. Cu-Sn/Pb solder bonds. Given good wetting (where 'wetting' means both the spreading of the solder on the surface and a good metallurgical bond with the formation of intermetallic compounds (IMCs)) there should be no reliability differences, because in good solder joints the interfaces are not directly involved in fatigue failures. There are however, differences in the pull strength of these solder joints (see Engelmaier, W., and B. Fuentes, "Alloy 42: A Material to be Avoided for Surface Mount Solder Component Leads and Lead Frames," Proc. Surface Mount International Conf., San Jose, CA, August-September 1994, pp. 644-655; also in Proc. Int. Electronics Packaging Conf. (IEPS), Atlanta, September 1994, pp. 503-516; also in Proc. 19th Ann. Electronics Manufacturing Sem., Naval Air Warfare Center, China Lake, CA, February 1995, pp. 5-20; also in Proc. NEPCON West '95, Anaheim, CA, February-March 1995, pp. 385-395; also in Soldering & Surface Mount Technology, No. 21, October 1995, pp. 20-25); the pull strength to Ni-based surfaces is lower. That however, has no reliability consequences because even the lower pull strength is much more than is needed for the loading conditions experienced even under abusive manufacturing, handling and shipping conditions. It needs to be said however, that it is more difficult to form properly 'wetted' metallurgical bonds to Ni-based surfaces than Cu-based surfaces because the dissolution rate of Ni into Sn is much lower than that of Cu. Therefore, you need more heat at reflow. I recommend a 10 to 15 C higher peak reflow temperature for Ni-based soldering surfaces; alternatively you could spend more time at a lower peak temperature, but that is not practical in most cases unless you use vapor phase reflow. Werner Engelmaier Engelmaier Associates, Inc. Electronic Packaging, Interconnection and Reliability Consulting 23 Gunther Street Mendham, NJ 07945 USA Phone & Fax: 973-543-2747 E-mail: [log in to unmask] *************************************************************************** * 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] * *************************************************************************** *************************************************************************** * 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] * ***************************************************************************