This has been talked to death, its a "Unix vs. Micro$oft" or "Internet Explorer vs. Netscape" or "vi vs. EMACS" type religious argument. Why beat a dead horse? -- George Patrick Tektronix, Inc. Central Engineering, PCB Design Group P.O. Box 500, M/S 39-512 Beaverton, OR 97077-0001 Phone: 503-627-5272 Fax: 503-627-5587 <http://www.tektronix.com/> http://www.tektronix.com <http://www.pcb-designer.com/> http://www.pcb-designer.com It's my opinion, not Tektronix' -----Original Message----- From: westfeldt [mailto:westfeldt_nbcd@xxxxxxxxx] Sent: Friday, October 29, 2004 14:29 To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: 0.5 mm BGA, whew! Regarding mils vs mm, I have often used copy commands to fanout various bga patterns. This is a pain, and gives later drc trouble, if the units are wrong. Patrick Westfeldt, Jr. North Boulder Circuit Design _____ From: Gary MacIndoe [mailto:gary.macindoe@xxxxxxx] Sent: Friday, October 29, 2004 10:06 AM To: Allegro Forum Subject: [PCB_FORUM] 0.5 mm BGA, whew! All, Well, it seems to be a slow day on the Forum, so I'll through out a relatively involved set of questions! We are looking into using a 0.5 mm BGA in a very dense design, so big time HDI practices will come into play: micro vias (MVs), probably even stacked micro vias (SMVs), in order to fan out on several layers. - would you use the micro vias in pad or not? Why? Build them into the symbol? - how can you have the micro vias built into the symbol if you don't know which balls will go down to which layer? - I will make the 0.5 mm BGA Allegro symbol with the drawing units set to Millimeters, but would like to keep the design database set to Mils. Is this the way most of you have done it? - if the symbol is set to Millimeters and the design set to Mils, this makes dropping the micro vias (in pad or not) after the BGA symbol is placed in the design tricky. Any other way to get around this? - So, setting up blind/buried micro vias should be the same as any blind/buried via. How about SMVs? If you have a micro via set up for layers 1-2, 2-3, 3-4, etc., how do you avoid the DRCs when you stack them (same X,Y)? My head is about spinning trying to comprehend all of this micro via/stacked micro via stuff! Any help from someone that has already used a 0.5 mm BGA on a very dense design with stacked micro vias would be greatly appreciated!! Thanks in advance, Gary E. MacIndoe PCB Design Engineer Advanced Micro Devices, Inc. Longmont, Colorado