Art, First, thank you so much for following this thread on Hi-Freq materials and giving us the suppliers information. I have been working with these issues the last couple weeks and want to give some input I've collected. I hear very good things about Rogers material, and have no complaints with using it, if necessary. But, some info has crossed my hands, and I'm not sure I have need for what Rogers can give me, for a cost $$. I had a couple board manufactures in here, and the rep from GE (makers of Getek material. The fab shops have no qualms using Getek, and the costs are very much in line with FR4 material processing. Maybe 15-20% more per lot. But, I have published data from GE concerning Getek material up to 12Ghz. And, they supply a spreadsheet so you can calculate your own stackups, with whatever frequencies you use to give you your impedance values. With this, I can do my 2Ghz design on Getek material, and quite possibly acheive +/- 2% tolerance! They also market an impedance "simulator" which goes WAY beyond any impedance "calculator" I've seen available. By simulator I mean it will simulator all the factors effecting your stackup, not just layer to layer! I'm working to purchase it ASAP. It's very impressive. Now, for costs... From what I could gather Getek material ($4.07) is not quite 2X as much as FR4 material (~$2.75 for .021 core material), and Rogers 4003 material ($9.95) is not quite 4X FR4 material. These values are disputable, as they will change from supplier to supplier, and from quantity to quantity, but those are value we currently look at. As I said, I like all these materials, for whatever application they apply to, but at 2Ghz (and any impedance designs, now) I'll use the Getek material. If it doesn't work, I'll surely go back online and bitch. Thanks again Art. :) Mitch Morey Sr PCB Designer NSI Communications San Diego (619)657-5338 >>> "Arturo J. Aguayo" <[log in to unmask]> 06/02/98 07:12am >>> Frank, You are correct in that each application is different and one can use FR4 in some applications greater than 1 GHz. Loss is an important factor, but we have seen designers switch from FR4 to a high frequency material because of dielectric tolerance too. That I'm aware of, there is no tolerance (or at least published) in dielectric tolerance for FR4 or many other high Tg materials, only on those designed specifically for RF/microwave applications. Because of that fact, some FR4 boards require much tuning to get them to work, this adds overall cost to the finished circuit and in some cases it is cheaper to got to a more expensive laminate and eliminate tuning. Each application is different and if I were desining a board I would give FR4 a shot also. Let's face it, if it works after looking at all costs then there is nothing that somebody like me (working for a supplier of high frequency laminates) can say to convince you to switch away from FR4 (but there are cases down to 500 MHz, digital, where the change has happened). regards Art Aguayo [log in to unmask] www.rogers-corp.com/mwu/ [log in to unmask] wrote: ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################