Thanks, Gert I actually intend to use 4-mil traces on a 3-mil thick Polyamide in a Microstrip configuration. Will this configuration get me tighter tolerances than the +/-20% I asked about? And I don't mean to include surrounding materials or bending, just the fabrication process itself Regards Itzhak -----Original Message----- From: Havermann, Gert [mailto:Gert.Havermann@xxxxxxxxxxx] Sent: Tuesday, December 01, 2009 11:42 AM To: Hirshtal Itzhak Subject: AW: [SI-LIST] AW: Multi-Giga-Hertz Rigid-Flex Feasibility Hello Itzhak, sorry for the typo, I meant 0.08mm (3mil). Flex base material is usually very thin (1mil) ant for impedance control, that means small traces. 3-4mil are harder to achief on flex than on FR-4, the yield will be lower, thus cost will rise. There are thicker laminates available, but they also cost extra. Stripline on Flex isn't common, but in critical cases where you can not control the flex in its final environment, you should switch to stripline to avoid problems in the field. BR Gert -------------------------------------------------------------------------- Absender ist HARTING Electronics GmbH & Co. KG; Sitz der Gesellschaft: Espelkamp; Registergericht: Bad Oeynhausen; Register-Nr.: HRA 5596; persönlich haftende Gesellschafterin: HARTING Electronics Management GmbH; Sitz der Komplementär-GmbH: Espelkamp; Registergericht der Komplementär-GmbH: Bad Oeynhausen; Register-Nr. der Komplementär-GmbH: HRB 8808; Geschäftsführer: Torsten Ratzmann -----Ursprüngliche Nachricht----- Von: Hirshtal Itzhak [mailto:ihirshtal@xxxxxxxxxx] Gesendet: Sonntag, 29. November 2009 08:59 An: Havermann, Gert; si-list@xxxxxxxxxxxxx Betreff: RE: [SI-LIST] AW: Multi-Giga-Hertz Rigid-Flex Feasibility Hello Gert First - thank you for your contribution. I have a few questions regarding your email: 1) You refer to a trace width of 0.8mm as "small". This is a 31.5mil width, which I hardly call "small"! I regularly use 3-4 mil trace widths in my designs. Is there something different in Flex circuits, which enforces me to use such LARGE traces (compared to my regular traces)? 2) I see the problem you mention for the Microstrip configuration. Is it common to use Stripline on a flex circuit? I was told this is impractical, although I'm not sure what the reason is. Thanks Itzhak Hirshtal Elta -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Havermann, Gert Sent: Tuesday, November 24, 2009 4:19 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] AW: Multi-Giga-Hertz Rigid-Flex Feasibility Hello Itzhak , All Polimide (Kapton) materials will do the job from a loss and dispersion prospective. The tolerance you mention seems to be unreasonable high for an etching tolerance. I did Flex designs with impedance control, 100Ohm +/-10Ohm, 0.8mm tracewidth without problems (of corse I had to pay extra for the small trace width). If you refer to an impedance tolerance due to bending and surrounding material, thats another story. If you design it in microstrip (as you are planning it), then everithing touching the flex might change your impedance. Designing it in stripline decreases the flexibility of the flex and increases cost. Look for Dupont, Grace Electron or Shengyi Flex materials for more info. BR Gert -------------------------------------------------------------------------- Absender ist HARTING Electronics GmbH & Co. KG; Sitz der Gesellschaft: Espelkamp; Registergericht: Bad Oeynhausen; Register-Nr.: HRA 5596; persönlich haftende Gesellschafterin: HARTING Electronics Management GmbH; Sitz der Komplementär-GmbH: Espelkamp; Registergericht der Komplementär-GmbH: Bad Oeynhausen; Register-Nr. der Komplementär-GmbH: HRB 8808; Geschäftsführer: Torsten Ratzmann -----Ursprüngliche Nachricht----- Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] Im Auftrag von Hirshtal Itzhak Gesendet: Dienstag, 24. November 2009 14:21 An: si-list@xxxxxxxxxxxxx Betreff: [SI-LIST] Multi-Giga-Hertz Rigid-Flex Feasibility Hello All My project manager intends to use a rigid-flex design in our next high-speed board. He wants to route a few pairs of 3.125GHz from a rigid section to another one through a flex section. Does anyone know if this is feasible? I found out that the 2 sections, although spec'd to be 100-Ohm diff impedance, can still differ substantially - as much as 30%, because the tolerance of the flex section is +/-20%. Can such a design work for a substantial trace length? Should I restrict the trace length on the flex section to be no more than an inch or so, in order to reduce the impact of the supposed non-uniform impedance? I intend to use a 2-layer flexible laminate with the pairs on one layer and a Ground reference on the other one. Any advice on this matter would be helpful Thanks Itzhak hirshtal The information contained in this communication is proprietary to Israel Aerospace Industries Ltd., ELTA Systems Ltd. and/or third parties, may contain classified or privileged information, and is intended only for the use of the intended addressee thereof. If you are not the intended addressee, please be aware that any use, disclosure, distribution and/or copying of this communication is strictly prohibited. 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