All: Having a problem on the Flipchip package substrate layer stackup to lower the utility plane inductance. The original design stackup -------- bump pad, VSS1 (interested in the partial inductance of this plane) -------- signal -------- VDD1, VSS1 (small VSS1 plane connected to the VSS1 bump pads on layer 1 and connected back to VSS1 on layer 1 and layer 7) -------- VSS -------- VDD1 ------- signal ------- BGA pad, VSS1 The modified design stackup -------- bump pad, VDD1 (interested in the partial inductance of this plane) -------- signal -------- VSS1 -------- VSS -------- VDD1 ------- signal ------- BGA pad, VSS1 We expected the partial inductance of the VSS1 plane in the modified design stackup to have lower value. But it turned out to be higher than the original design. We used PAKSI-E tool to extract the partial inductances. This tool takes the gerbers as the input files. There was no input violation and the tool was consistent in providing reasonable results in other designs. Can anybody help me understand why the inductance is higher in the modified design. Thanks in advance for any help, Musawir ___________________________________________________________ Musawir Chowdhury musawir@xxxxxxxxx agere systems Tel: 610-712-8175 Packaging & Interconnect Technology Fax: 610-712-5818 Design Integration Allentown, PA ------------------------------------------------------------------ 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 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