Hi Canes If the BGA has planes, your PDS is better then the One Layer QFP package. Can you just remove Power ground leads from the BGA, not so simple. Let's look at these two packages; JEDEC-MS-034b.pdf BGA 256 lead, Body size 17x17mm JEDEC-MS-029A.pdf QFP 256 lead, Body size 28x28mm 1. Dose the QFP meet PDS budgets as is? 2. Dose the QFP meet SSO/SSI requirements? 3. If Powers are removed from BGA will PDS be met? 4. If grounds are removed from BGA will PDS be met? 5. If return paths are remove from BGA will SSO/SSI be met? 6. For NEXT and FEXT on the QFP I will see two aggressors within 1.0mm on either side of the victim, on the BGA I will see eight aggressors with in 1.0mm, But the BGA has a return path that can reduces over all coupling. Assuming four quadrants on QFP Package, 12 powers, and Ground (6 GND, 4 VDDI 2 VDD) per quadrant this leaves 52 IO, 4 IO per return path, add 4 Ground, or 2 Ground and 2 power, this leaves 48 * 4 =3D 192 lead for signals (or approximately 4 IO per return path), This should be the same for the BGA, although, if Number 3-6 are not an issues, then yes can reduce the PDS on the BGA. Just my thoughts, Thanks, Walter -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Canes Venatici Sent: Monday, April 23, 2007 6:40 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] BGA Vs QFP Hi all, I'm having some confusion related to BGA. I believe BGA can have planes for ground, core vdd, io vdd etc. Since the planes are equipotential, can I assume for same number of power pin count in QFP, I can reduce balls in BGA. For ex.,=20 I have a common die for two packages say, QFP and BGA with same number of pads for both packages.=20 But I want to reduce the power pin count by taking advantage of planes in BGA. Is it possible? Could anyone throw some light on it? Regards Canes __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around=20 http://mail.yahoo.com=20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: =20 =09=09//www.freelists.org/archives/si-list or at our remote archives: =09=09http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: =09=09http://www.qsl.net/wb6tpu =20 The information contained in or attached to this email may be subject to = the Export Administration Regulations (EAR), administered by the U.S. Dep= artment of Commerce, or the International Traffic in Arms Regulations (IT= AR), administered by the U.S. Department of State, and may require an exp= ort license from the Commerce or State Department prior to its export. A= n export can include a release or disclosure to a foreign national inside= or outside the United States. Include this notice with any reproduced p= ortion of this information. ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu