Alan, This sounds like a lot, 10 per side over the drill (30 mil anti-pad for a 10 mil drill). When you have several high speed traces at minimum spacing between vias, that's more than you can afford. Those high speed traces don't like to run over the hole (anti-pad) in the reference plane. Thanks for the reply. Gary E. MacIndoe PCB Design Engineer Fort Collins, Colorado amd.com gary.macindoe@xxxxxxx ________________________________ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Ritter, Alan Sent: Friday, December 14, 2007 12:25 PM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: Anti-pads Smallest anti-pad we have used is 25 mils for 8-mil (BGA) and 10-mil vias. 35 mils for 15-mil "power" vias, etc. We figure a minimum of 10 per side over the drill. /s/jar (alan.ritter@xxxxxxxxxx) http://www.mtritter.org ________________________________ From: Macindoe, Gary [mailto:Gary.Macindoe@xxxxxxx] Sent: Friday, December 14, 2007 1:11 PM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: Anti-pads Thanks Gerry. I haven't thought about it for quite a while, I was forgetting that anti-pad to drill is what matters. I suppose with an anti-pad that small, you have to make sure you suppress unused inner pads. A drill of 10 mil probably has a 20 mil pad, so a 16 mil anti-pad to a 20 mil pad would be too close otherwise. Thanks again, Gary Gary E. MacIndoe PCB Design Engineer Fort Collins, Colorado amd.com gary.macindoe@xxxxxxx ________________________________ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Gerry Meier Sent: Friday, December 14, 2007 11:48 AM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: Anti-pads 16 mil over the drill size - 10 mil drill 26 mil anti-pad Gerry Meier, Sr. PCB Designer Freedom CAD Services. Inc Voice: (256)776-7470 or (603) 864-1350 Email:gerry.meier@xxxxxxxxxxxxxx visit us at http://www.freedomcad.com ________________________________ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Macindoe, Gary Sent: Friday, December 14, 2007 12:28 PM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Anti-pads Hey guys, We haven't thrown around anti-pads for a while! What is the smallest anti-pad for an inner plane that you have successfully used? Has anyone used down to 5 mils a side anti-pad to pad? Thanks, Gary Gary E. MacIndoe PCB Design Engineer Fort Collins, Colorado amd.com gary.macindoe@xxxxxxx This correspondence and any attachments are considered confidential. If you are not the intended recipient, please notify Freedom CAD Services, Inc. immediately by either replying to this message or by sending an email to operations@xxxxxxxxxxxxxx; please destroy all copies of this message and any attachments. Thank you. EMAIL DISCLAIMER Please Note: The information contained in this message may be privileged and confidential, protected from disclosure, and/or intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any disclosure, distribution, copying or other dissemination of this communication is strictly prohibited. If you received this communication in error, please immediately reply to the sender, delete the message and destroy all copies of it. Thank You