See answers to your questions below. Thanks, Yuan Li On Wed, 12 May 1999, Alderete, Michael wrote: > Li- > > 1) Is this a full array of BGA balls, or a perimeter array? Full array > 2) In larger packages, are balls under die, or edges of die? Some are under die, a few under edge of die. Have you found that fatigue life is much lower if balls under the edges of die? > 3) Is the cross section, and hence construction, of both types known to you? > If your aren't sure, a cross section on each type will confirm this, > including die and bond line thickness, (BT) substrate thickness, etc. Yes, it is known to me. > 4) I'm not too familiar with TBGA construction. Could it be that BT > substrates are much stiffer (in x-y plane) than TBGA? Also, are there heat > spreaders in these packages? > No heat spreaders. Tape substrate is much thinner (2 mils VS 24 mils for BT sub.) > > -Michael Alderete > > Li Yuan wrote... > ------------------------------ > > Date: Wed, 12 May 1999 13:11:40 -0600 > From: LI YUAN <[log in to unmask]> > Subject: BGA Solder joint reliability > > Dear BGA Reliabilty Experts: > > I have done FEM simulations for BGAs and have found some results I cannot > explain. Hope you can enlighten me on it. > > I modeled BT-based BGAs and tape-based BGAs (both cavity up) under 0-100C > 1 cycle per hour condition. For BT BGAs, with the same die size, the > larger the package, the better the mean fatigue life. This phenomina may > be attributed to die/package ratio, the bigger the die/package ratio, the > worse the fatigue life. However, for tape BGAs (tape substrate is much > thinner than BT substrate), the result is the opposite. With the same die > size, the larger the package, the worse the fatigue life. > > Can someone explain why the difference between BT and Tape BGAs? > > Best regards, > > > Yuan Li > > ------------------------------ > ################################################################ 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 ################################################################