Jim, I am not sure if I understood you correctly but here is my two cents for what it is worth. If there is copper under the area that is being analyzed by SEM/EDX, you may be detecting the copper from that source. The SEM/EDX system uses an accelerating voltage. Years ago when I ran this type of system, we used an accelerating voltage of either 10 Kv, 20 Kv, or 30 Kv. The higher the Kv, the deeper the penetration of the energy beam into the surface that is being analyzed. It may be possible that the SEM/EDX is penetrating through the surface layer of interest and into the layer underneath. Wade Oberle Manutronics, Inc - Division of Sanmina -----Original Message----- From: Jim Marsico 516-595-5879 [SMTP:[log in to unmask]] Sent: Thursday, May 13, 1999 7:26 AM To: [log in to unmask] Subject: [TN] BGA FAILURE ANALYSIS Good Day Technet: First, a little background... We're in production using a 228 ceramic BGA for a military contract. The base material of the component is gold plated nickel, prior to solder ball attachment. The gold plating is very thin, around .25 microns. We've been experiencing approximately 5% (components, that is, not solder joints) open circuits found at in-circuit testing (ICT). Upon removal of the BGA (Air-Vac system) from the board, the specific ball location where the open was identified at ICT shows no solder remaining on the component, where all other locations has solder remaining. What does remain is a dull, gray, crystalline metallization. SEM/EDX analysis shows Ni/Sn and Cu/Sn. It is presumed that the Ni/Sn is the intermetallic layer created from the nickel base material and the tin in the solder. What puzzles me is the presence of the copper-tin crystallites. Since there is no copper in the solder or on the component, is it possible that this copper has migrated all the way up from the board pad to the component/solder interface? Thanks in advance... ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################