John, when the plates of a cap are parallel to the planes, eddy currents block field penetration to the upper plates through the cavity. The field still goes around the terminal metalization. This makes a resonant cavity. Steve. At 10:50 AM 5/22/2006, Hill, John wrote: >Mark,=20 > >We have uploaded an application note from American Technical Ceramics >concerning placing capacitors vertical and horizontal. The URL is: > >http://si-list.org/files/tech_files/ATC%20select_cap_wireless.pdf > >I have also sent an e-mail to the application engineer about the issue >of eddy currents limiting the field. The data in the application note >does not look like it supports the idea and I do not understand the >physics.=20 > >John > > >=20 > >--------------------------------------- >The information in this email and attachments hereto may contain legally = >privileged, proprietary or confidential information that is intended for = >a particular recipient. If you are not the intended recipient(s), or the = >employee or agent responsible for delivery of this message to the = >intended recipient(s), you are hereby notified that any disclosure, = >copying, distribution, retention or use of the contents of this e-mail = >information is prohibited and may be unlawful. When addressed to Takata = >customers or vendors, any information contained in this e-mail is = >subject to the terms and conditions in the governing contract, if = >applicable. If you have received this communication in error, please = >immediately notify us by return e-mail, permanently delete any = >electronic copies of this communication and destroy any paper copies. >--------------------------------------- >-----Original Message----- > >From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] >On Behalf Of Mark Randol >Sent: Monday, May 22, 2006 10:33 AM >To: si-list >Subject: [SI-LIST] Re: Capacitors arrays. worth it or not? > > > -----Original Message----- > > From: si-list-bounce@xxxxxxxxxxxxx=3D20 > > [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry Martinson > >=3D20 > > I've always wondered how discrete cap performance is affected=3D20 > > if the caps plates are parallel with the underlying plane or=3D20 > > if they are perpendicular. I'd think that having them rolled=3D20 > > 90 degrees > > (perpendicular) might make them perform better in some=3D20 > > regions. I wonder how this would extend to arrays and=3D20 > > whether arrays are configured rolled or not. Does anyone=3D20 > > know? =3D20 > >American Technical Ceramics (ATC) used to recommend 'vertical' placement >of their porcelain caps for just this reason. I've seen it make several >100MHz's of difference in the measured resonance frequency. That was on >a relatively thick 2 layer PCB, so on a board with a thinner component >to ground layer spacing this could be more significant <guess>. I >didn't find it on their web site, but here is their link. > >http://www.atceramics.com/ > >Now how much of this was due to plate coupling to the substrate, or >reduced effective capacitance and inductance because of current crowding >towards the new 'bottom' of all the plates, beats me. It seems to me in >the horizontal orientation, the upper plates would have slightly more >inductance due to the greater loop area. Which effect dominates, >capacitance or inductance? =3D20 > >The problem at the time was fixed, so we didn't investigate further. > >-- >Mark Randol, RF Evaluation & Application Engineer >Not speaking for my company, etc >------------------------------------------------------------------ >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 FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > >List technical documents are available at: > http://www.si-list.org > >List archives are viewable at: =20 > //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 >------------------------------------------------------------------ >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 FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > >List technical documents are available at: > http://www.si-list.org > >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 > ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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