The vias can be drilled with a 0.2mm tool and with the trace intersection improved to maintain a reliable connection - 2:1 in pads less than .020" is where we see the minimum pad to hole to keep the trace integrity. With a PTH via of .018" the same drill can be used - the increasing aspect ratio will require some attention to plating but is not that exotic. You can purchase 0.25mm drills which are also an option. Via types in this case will have 90 degree breakout, not affecting minimum trace width at pad intersection. Cavity features will need to be assessed for depth, size, finish, etc. A milled non-plated cavity is fairly standard, but plated and build-up cavities can increase to PCB cost of mfg. Jeffrey Bush Director, Quality Assurance and Technical Support VERMONT CIRCUITS INCORPORATED 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302 Voice: 802.257.4571.21 Fax: 802.257.0011 http://www.vtcircuits.com -----Original Message----- From: [log in to unmask] [mailto:[log in to unmask]] Sent: Tuesday, May 03, 2005 1:56 PM To: [log in to unmask] Subject: [TN] Annular ring:- What should we sign up for ???? We have a tough brd to manu. and want to know what kind of annular ring requirement should we sign up for. This is for SPACE so it requires IPC-6012 class 3, w/ exceptions to annular ring. 12 layers 1) Burried vias 7-11 2) Burried vias 6-11 3) Blind vias 6-12 4) Burried and blind vias have 16 mill pads for vias (thickness ~ 60 mils) 5) Thru holes (~90 mils) 18 mil pads. 6) Cavity brds w/ broad side coupled diff. impedance control Thanks for your help in advance Rush [log in to unmask] (mailto:[log in to unmask]) 818-768-3919 --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------