Zhiping, static applications where flex is used to make non-planar shapes are fine with solid planes. Regards, Steve. At 06:10 PM 8/23/2005 -0700, Zhiping Yang \(zhiping\) wrote: >Hi, > >I had an impression that the planes on flex are not really solid plane. >It is more like a mesh with small holes. Is it also true for embedded >capacitance on flex? If so, I assume it will reduce the total available >capacitance. Can someone confirm it? Thanks. > >Best regards, > >Zhiping > >-----Original Message----- >From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] >On Behalf Of steve weir >Sent: Tuesday, August 23, 2005 5:48 PM >To: Larry.Smith@xxxxxxx >Cc: ray.anderson@xxxxxxxxxx; adsurevv@xxxxxxxxx; si-list@xxxxxxxxxxxxx >Subject: [SI-LIST] Re: [SI-LIST]: Embedded capacitance on Flex..?? > >Larry, they are fun materials, aren't they? > >Best Regards, > >Steve. >At 05:42 PM 8/23/2005 -0700, Larry SMITH wrote: > >Steve - Yes, we have sampled both DuPont and 3M. Dupont is very > >flexible, almost like saran wrap. The 3M material is good for hard > >boards but is about as flexible as a potato chip. Snaps like one too, > >I tried it.. > > > >regards, > >Larry > > > >steve weir wrote: > > > Larry, DuPont and 3M both have thin dielectric with elevated Ers > > > that is nice stuff. > > > > > > Some caution is warranted though depending on the specific > > > application. High Er material can do good things as you said. For > > > a > > given > > > skin and dielectric loss, the peak magnitude of the parallel > > > resonant peak falls approximately as the inverse square root of Er. > > > > It tends to be even better than that as higher dielectric loss pulls > > > > down the peak as well. But there are some potential rocks in that >stream: > > > > > > 1. Reduced board modal resonant frequencies, good for damping, > > > potentially bad if too low 2. Reduced board to discrete capacitor > > > parallel resonant > > frequency. Can be > > > a good or bad thing. Introduces more variables to discrete bypass >design. > > > 3. Increased risk of quarter wave resonance within power delivery > > > band between discrete caps and IC die. > > > 4. Much higher material cost. > > > > > > Best Regards, > > > > > > > > > Steve. > > > At 01:24 PM 8/23/2005 -0700, Larry Smith wrote: > > > > > >>Virendra - I believe that Dupont has some thin, flexible dielectric > > >>that can be loaded with ceramic to bump up the dielectric constant. > > >> > > >>We have found that the best value comes from thin dielectric because > > > >>it both reduces inductance and increases capacitance resulting in > > >>lower impedance. The lower power plane impedance produces more > > >>damping, which is a good for reducing power plane resonances. > > >> > > >>By increasing the dielectric constant alone (no dimensional changes) > > > >>the capacitance per square area is increased but it turns out that > > >>the capacitance available to a power consumer with in a given time > > >>frame (i.e. 1 nSec) is the same. This is because the velocity of > > >>electromagnetic propagation goes down with increasing dielectric. > > >>The cylindrical wavefront that goes out from a disturbance > > >>"uncovers" the same amount of capacitance per time, independent of > > >>the dielectric constant. > > >> > > >>So if you are looking for high frequency capacitance to satisfy > > >>those fast edges, thin dielectric is good, high dielectric constant > > >>is neutral. > > >> > > >>regards, > > >>Larry Smith > > >>Sun Microsystems > > >> > > >>Ray Anderson wrote: > > >> > > >>>Typically the way I've seen it done in the past is to use a very > > >>>thin dielectric material (~2 mil thick) to achieve the higher than > > >>>usual capacitance. > > >>> > > >>>Most hi-k materials are loaded with some sort of ceramic material > > >>>which tends to make them somewhat less than flexible which could be > > > >>>an issue with a flex board. > > >>> > > >>>Note that the materials people are always developing new and > > >>>innovative solutions, so what was true a couple of years ago when I > > > >>>looked at the issue may no longer be the case. > > >>> > > >>>-Ray > > >>> > > >>>-----Original Message----- > > >>>From: si-list-bounce@xxxxxxxxxxxxx > > >>>[mailto:si-list-bounce@xxxxxxxxxxxxx] > > >>>On Behalf Of Virendra > > >>>Sent: Tuesday, August 23, 2005 12:11 PM > > >>>To: si-list@xxxxxxxxxxxxx > > >>>Subject: [SI-LIST] [SI-LIST]: Embedded capacitance on Flex..?? > > >>> > > >>>Hello All, > > >>>Does anyone have experience with embedded capacitance (wih high K) > > >>>on a flex circuit board? If yes, are there any issues with bending > > >>>the part of the flex with the high k material..? > > >>> > > >>>thanks in advance, > > >>> > > >>>virendra > > >>> > > >>>__________________________________________________ > > >>>Do You Yahoo!? > > >>>Tired of spam? Yahoo! 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