Hi Sven-Eric It is a matter of fact that the solder joints of TSOP's are less reliable than the ones of packages with high standoff since it is the length of the leads which absorbs most of the deformation due to the CTE mismatch of component and PCB. Long leads deform easier than short leads. Additionally if the leadframes of TSOP's are made of Alloy 42 than the leads are stiff compared to copper leads. Using copper leads instead of Alloy 42 eases the problem to a certain extend. However, I believe it is important to consider the environment the product is used in. Namely the temperature swing, the temperature extremes the temperature gradient and the reliability goal of the solder joints ( As Werner already mentioned, there is nothing wrong with TSOP's per se ). In my opinion the reliability of these solder joints has to be estimated for the application their used in, since even a material combination that is potentially harmful might lead to a reliability of the solder joints that is well within the requirements for a given stress. Let's say one uses TSOP's on FR 4 in an office environment 20- 30deg. C and the equippment sees a temperature swing of 40deg.C with a ramp of 1 deg. C/min. When switched on and off once a day. I don't see a point why not using TSOP's unless the thing has to live 100 years. Reliability testing does not always mean to find the evil part in an assembly corrupting the reliability of the whole equippment but also to find out whether a technology that is absolutely disastrous for some applications but has advantages ( price, space ) may be used in an application with moderate stress. Therefore I think it doesn't make sense to use data from tests with extreme testconditions to estimate the reliability for a much less severe application without checking whether the testconditions are applicable to the real stress. Besides that's the work Werner and I are living of so it's got to be important. Best regards Guenter Grossmann Swiss Federal Institute of Technology Reliability Laboratory ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################