Another problem with the QFN center pad is the thermal vias in the pad, and their effect on solder distribution. We don't get a lot of feedback from manufacturing, but we do know we were having soldering issues, even after segmenting the stencil. They are using a 4 pad pattern, with a step down, but were still complaining. I moved the thermal vias into the web of the stencil (non-pasted areas), thinking maybe the vias were either drawing solder away unevenly or outgassing and lifting the part. I don't know the effect it had, but the complaints stopped. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------