Yves: We have just started into the 1.0mm BGA's ourselves. Our PCB Assembly yields have been identical (actually slightly higher) than the 1.27. Of course we are in the <300 ball regime for the 1.00, whereas we were in the >400 ball range for the 1.27. Package size appears to have a great deal to do with our yields. If we use a 1.00 27X27 at 196 balls, we get better yeilds than a 35X35 1.27 at 196 balls. Likewise a 452 ball 35X35 1.00 yielded better than a 40X40 452 1.27mm package. Most of the theories here have something to do with laminar coplanarity. The BT substrate moves considerably (2~3X) in the Z axis during reflow (when compared to all of the other materials). Constrictions to this movement and levers exist where the overmold package body meets the BT; likewise, the center configuration will also be a localized constrictor. Finally, we have also seen a vriation in yields when considering the number of layers in the BT substrate as well. It may be where our process is optimized (we originally did it for 4 layers). With 2 layer or 6 layer subs we tend to get lower yields. So what we have don is required all substrates to be at the same layer count on a given assembly (i.e., no mixing of # of layers within a given assembly). 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: Yves Trudell [SMTP:[log in to unmask]] > Sent: Friday, November 13, 1998 9:20 AM > To: [log in to unmask] > Subject: [TN] 1mm PBGA Assembly > > Dear TechNetters, we're venturing into assembling 1mm BGAs onto our > PCBs. > We're starting with a 196-pin PBGA package. > If you have experience with assembling this package technology onto > PCBs, > what kind of assembly (not electrical) yields (DPMO) do you consider > to be > good? If you don't feel comfortable in sharing this information in a > quantified manner, how does it compare to other PBGA packages such as > 1.27mm > pitch? > > Yves Trudell > Nortel, Wireless Networks Calgary > Quality System Engineering > > ################################################################ > 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 ################################################################