I've posted a rather interesting image to Steven Gregory's website. You can view it at the attached link: http://stevezeva.homestead.com/files/QFPcrud.jpg It shows what we sporadically see on QPF solder joints with certain batches of boards from a PCB supplier. Other details are as follows: * Sn/Pb process * Always seems to occur at a certain QFP pad location of one specific board on a 6 board panel. * Solder paste & stencil have pretty well been ruled out. * This QFP is soldered on the second side reflow operation. * Occasionally we'll see black Crud float to the top of these pads after first side reflow. * If we print over this black crud & solder, sometimes we won't see any issue with the solder joint, sometimes we'll see as the image depicts, occasionally we'll cross section and see a thick black layer beneath the lead in the solder joint but the fillet around the lead looks fine. * Boards are HASL coated. (Horizontally I suspect). * Depending whom you believe, this row of QFP leads is either in the leading or trailing edge of the panel as it proceeds thru HASL. * Inspection of the boards prior to any reflow does not show any anomalies with the suspect pad. My belief is that dross is being included in these pads beneath the good HASL coating, and coming to the surface in our reflow operations. Any thoughts other thoughts on what this is and how to prove it would be appreciated. Rich K / KEDS --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 -----------------------------------------------------