Oh my... I misread your e-mail... You were talking about 40Gbits... I'm not sure the freq characteristics at that data rate... Perhaps you can expound on that a little more... :) Sorry for the confusion... old timers disease... :) Best regards, Bill Brooks PCB Design Engineer, C.I.D.+ Tel: (760)597-1500 Fax: (760)597-1510 Datron World Communications, Inc. Vista, California -----Original Message----- From: Brooks,Bill [mailto:[log in to unmask]] Sent: Thursday, March 15, 2007 1:31 PM To: [log in to unmask] Subject: Re: [DC] Information on multilayer boards with Teflon materials m ade using fusion bonding Hi Devon, Thanks for your help with my question before.. :) At 40GHz I would expect you to use PTFE and bond it to a metal plate much like we did when I was working in the 15GHz range, a Ku band transceiver project. But if this must be a multilayer board I would be looking for help or advice on how to proceed too. The Rogers Corp. applications development manager Cesar Santiago was very helpful in explaining the properties of their materials and making recommendations for our application. I also understand that PARC/Nelco has a wide variety of high freq materials available as well. I would be very interested to see what combinations you come up with for 40GHz signals. Best regards, Bill Brooks PCB Design Engineer, C.I.D.+ Tel: (760)597-1500 Fax: (760)597-1510 Datron World Communications, Inc. Vista, California -----Original Message----- From: Post, Devon [mailto:[log in to unmask]] Sent: Thursday, March 15, 2007 5:37 AM To: [log in to unmask] Subject: Re: [DC] Information on multilayer boards with teflon materials made using fusion bonding Jack, Thanks for your reply. The purpose of the board would be for 40+ Gbps signals. Unfortunately at these speeds anything with glass weave starts to affect the signals. The purpose for teflons is the loss tangents are very very low and, depending on the material, there is little to no glass weave. (for Bill Brooks) The last part of my statement about little to no glass weave is the important part here that differentiates what we talked about a couple of weeks ago. For those that would like to know more. The glass weave in laminates start to affect the signals at higher frequencies say above 10 GHz. The reason has to do with the signal traces and uniformity about the weave. The weave of the glass ebbs and flows like a wave, meaning there are peaks and valleys. If one of the signals of a differential pair were to be manufactured such that it resides over more valleys than it does peaks, and the other signal was over more peaks than valleys, the result would be that electrically at high frequencies the signals would not be aligned (this is an over-simplification of what is really going on). Even if the cad tool routed them to within a mil, or 25um, of each other, they could still be skewed significantly from a phase angle perspective. Why is this true? The instantanious dielectric constant that the signals see would be different. This causes the propagation velocity of the signal to be different for the two traces. At low frequencies we assume that the dielectric is uniform and therefore the dielectric constant is uniform, at high frequencies this is not as true. The end result is that the differential pair will have greater mode conversion, and there will be additional attenuation of the signal as it propagates through the board. This issue will need to be addressed during the design phase of a board as signal frequencies continue to increase in speed. Devon ======================================================================= Devon J. Post - C.I.D. Mayo Foundation <mailto:[log in to unmask]> 200 First Street SW Voice: (507) 538-5479 Sn 2-134C Fax: (507) 284-9171 Rochester, MN 55905 Internet: http://www.mayo.edu/sppdg/sppdg_home_page.html ======================================================================= ________________________________ From: Jack Olson [mailto:[log in to unmask]] Sent: 14 March, 2007 9:29 PM To: (Designers Council Forum); Post, Devon Subject: Re: [DC] Information on multilayer boards with teflon materials made using fusion bonding You may already know this, but there are materials with similar characteristics that are better suited to multilayer constructions, if you can get away with it. Maybe compare your needs to Rogers 4350? We tried that on a previous project and it was good enough for our 2.7GHz, and saved a ton of money too. (My only experience with teflon is single-layer circuits bonded to aluminum palettes, so I can't help you with your real question.) good luck, Jack On 3/13/07, Post, Devon <[log in to unmask]> wrote: Does anyone have a contact or companies that they work with, and are willing to share, that can build a multilayer board out of high-frequency teflon dielectrics using fusion bonding as their lamination method for these dielectrics. These would be research type boards with currently no mass production planned. Devon ======================================================================= Devon J. Post - C.I.D. Mayo Foundation <mailto:[log in to unmask]> 200 First Street SW Voice: (507) 538-5479 Sn 2-134C Fax: (507) 284-9171 Rochester, MN 55905 Internet: http://www.mayo.edu/sppdg/sppdg_home_page.html ======================================================================= ------------------------------------------------------------------------ --------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. 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