Earl, Just in case some might think it is impossibe, we have been using 14 layer, bgas-stuffed both sides, fine-line quads, 0402, etc,etc, for several years in, at least, 5 part numbers. We are now looking at 16 layers!!! Of course it is using thin core material and is NOT cheap!! So, as you pointed out, get with your fabricator(s) and check out their capibilities and review your documentation and end product requirements. This tended to be a science project, but since both the board fabricator and assembiler were involved from the begining, we have had minimual problems, but no show stoppers. Again, this has been in small quantities, 50-75 of each. Just another view. Bob Vanech Mango DSP P.S. Wish the snow would stop..AAAUUUUGGGGHHHH!!!! > First, a 12 layer board .062" thick? Don't think so if it's a serious board > requiring hole to pad registration and no breakout, etc. What are you > specifying for preg/core - 80% resin content with no glass? 10 layer boards > enjoy this privelage - not 12's without serious yield problems. > > The silver fill stuff is touted by some like Sanmina/Hadco but often for > capped vias that you might consider only when using sequential lamination. > This ensures micro vias or others be plated over the hole forming a flat > surface on the BGA pads. It's sort of like having vias in pads without > knowing it. You know the drill. > > Everyone, since 1980 has had this goal in mind and many of us did it then > as now. You must assess supplier process capabilities and your design > objectives, together with a cost picture, to make the right decision. The > whole concept is admirable but compromises can cost a bundle. > > Earl Moon > > -------------------------------------------------------------------------------- > - > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send the following message: SET Technet > NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > -------------------------------------------------------------------------------- > - --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------