Jay: As I understand it, you are putting passive components onto the substrate of the BGA and then soldering the BGA to the PCB. My first instinct is to ask why? If you have a cap or resistor that needs to be that close to the component, you're probably better off putting the passive into the silicon. Anyway, the typical substrate used in BGA's these days is BT. BT has a X/Y CTE of 14-17ppm/C; however, it has a z axis CTE of 48-64ppm/C. It is likely that you may be fighting the moving BT during reflow. As for other substrates, the only other materials I'm aware of are hi-temp materials using BN or BNC. These are costly by comparison and may not be appropriate. Hope this helps... > Bill Davis, Ph.D. > Diamond Multimedia Systems > Senior Scientist > Tel. 408.325.7868 > Cell. 408.888.5650 > e-mail: [log in to unmask] > > -----Original Message----- From: Jay Bitanga [mailto:[log in to unmask]] Sent: Thursday, January 14, 1999 1:10 AM To: [log in to unmask] Subject: [TN] BGA Substrate Hi Everyone, I would like to ask your opinions regarding our problem with our BGA board. You see, a problem occured during our placement of components, specifically 0402 comps, on the substrate. Because of the density of the circuit, a test point is mistakenly registered as a fiducial mark since it is vey close to the latter. The fiducial is square solid shaped (15 mils). We considered that the shape of the fiducial is the factor involved in the registration error so what we did was change the shape of the fiducial but adapted the same measurement of it (cross-hair). Is this possible ??? Are there also problems that we do not see ??? Are there standards available for substrates for BGA and other types of new technologies ??? Thank you very much for taking time in answering these questions. Any information is much appreciated. Regards, Jay Bitanga Electronic Assemblies Inc. [log in to unmask] ################################################################ 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 ################################################################