You might want to look at the new publication (March 2011) of IPC-7093, "Design and Assembly Process Implementation for Bottom Terminated Components". It won't resolve all of the issues for you, but it is a good introduction. Some of the Technet members were on the committee that developed it; Have any of you come across mistakes or weaknesses or addendum? surfin' the learnin' curve, Jack . On Tue, 11 Oct 2011 10:39:18 -0400, Karen Tellefsen <[log in to unmask]> wrote: >How does one do these calculations, what are the rules? > >Is there a web site that can provide guidance? QFN's are difficult to >solder well > >Karen Tellefsen - Electrical Testing >[log in to unmask] >908-791-3069 > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 16.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------