Thank You Stephen, I now have a better understanding of 0.8-MM. The Fear Is Gone. Appreciatively, Richard E Marion 169 Little Mill Road Unit 2 Sandown NH 03873-2554 HOME: 603-887-2266 CELL: 603-247-1610 FAX : 603-887-2936 -----Original Message----- From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Feehan, Stephen Sent: Wednesday, September 14, 2005 11:32 AM To: 'icu-pcb-forum@xxxxxxxxxxxxx' Subject: [PCB_FORUM] Re: .8-MM BGA Geometry Hi Richard, The top side solder mask for the bga pad is 16 mils, the same as the top. For the via's I encroach the solder mask so I use a 12 mil clearance for the top and the bottom vias can be 20 mil clearance so its possible to do a flying probe test. When routing inside the bga area keep in mind that you may need to reduce the etch because most fab houses like to have a min. of 4 mils from via to etch spacing. In my case the impedance required a 4 mil etch so I only needed to reduce the etch to 3.75 mils inside the bga's. If needed you can reduce the size of the via on inner layer to 19.5 mils. Regards, Stephen Siemens Communications, Inc. _____ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Richard E Marion Sent: Wednesday, September 14, 2005 10:29 AM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: .8-MM BGA Geometry Hello Stephen, The 20/10 Via keeps "popping up", must be a good choice. On the 16-Mil BGA Pad, what diameter Soldermask do you recommend? Thank you for sharing your experience with me. Sincerely, Richard E Marion 169 Little Mill Road Unit 2 Sandown NH 03873-2554 HOME: 603-887-2266 CELL: 603-247-1610 FAX : 603-887-2936 -----Original Message----- From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Feehan, Stephen Sent: Wednesday, September 14, 2005 9:55 AM To: 'icu-pcb-forum@xxxxxxxxxxxxx' Subject: [PCB_FORUM] Re: .8-MM BGA Geometry Richard, You can start with a 16 mil bga pad and a 20 mil pad / 10 mil drill with a 28 mil anti pad for the via. In some designs I use the via in pin technology for all the gnd pins of a 0.8mm bga. The drill of the micro via is 4 mils and is build into the pad. Typically, I make sure Layer 2 is a gnd plane so all the micro vias hit directly into the plane. Call Merix Corp, they have local reps in MA/NH. Stephen Siemens Communications, Inc _____ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Richard E Marion Sent: Tuesday, September 13, 2005 6:27 PM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] .8-MM BGA Geometry Dear Forum, My Client is utilizing a 0.8-MM SDRAM Package. The smallest BGA Pitch I have dealt with so far is 1.0-MM. The Fabrication/Assembly Vendors are yet to be determined. The PCB "target" construction is 0.062-Inch 14-Layer, three sets of dual embedded stripline. No Blind/Buried Vias (all Thru Via). Questions: 1. Any recommendations for local (NH-MA) Fabrication/Assembly Vendors capable of working with this BGA Geometry? 2. BGA SMT Pad Diameter? 3. BGA SMT Soldermask Diameter? 4. Thru Via Drill? 5. Thru Via Pad Diameter? 6. Alternatively, is Via-In-Pad an option? 7. Any chance of ATE Testing 0.8-MM Pitch? Thank You, Richard E Marion 169 Little Mill Road Unit 2 Sandown NH 03873-2554 HOME: 603-887-2266 CELL: 603-247-1610 FAX : 603-887-2936