Hi all, Thanks Bill for the copy of the presentation. We are currently designing a 16 layer PCB with through hole vias, that we have to attach a 1200 pin, 1mm pitch, full array device to. The stackup actually looks pretty close to the one on page 12 of the presentation. This design is a is a first for us, and from the information contained in the presentation, it looks like we are heading down the right track. The cost adders for HDI made for interesting reading. I am not wanting to cause trouble before Mr Shoot gives his presentation, but I have a question regarding the use of the 3 mil prepregs shown in the stackup on page 12 of the presentation. I would assume that this would be one prepreg thickness only. I have had feedback from our board suppliers, and have been on courses, that say that it is preferable to lay up 2 prepregs. (This is to avoid potential shorts?). I will be asking our suppliers this question too, up to now this has not been an issue. Any does anyone have any comments on this? Will using one prepreg cause problems? (Our stackup came to around 70 mil thick, with 10 mil drilled holes, therefore aspect ratio = 7:1, so is manufacturable, we are still discusing details with our suppliers) Regards, Steve. ------------------------------------------------------- Steve Kingdon 27 Nazareth Avenue PCB Layout Engineer PO Box 8011 Allied Telesyn Research Christchurch phone +64 3 339 9223 New Zealand fax +64 3 339 3002 email: [log in to unmask] web: http://www.alliedtelesyn.co.nz/ ------------------------------------------------------- --------------------------------------------------------------------------------- DesignerCouncil 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 DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil 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 ---------------------------------------------------------------------------------