Ted, (Glad to see your back) I don't know the answers you're asking about as far as loss due to the metals you've outlined. I have heard that Nickel on Microwave assembly's requires to be characterized due to the metal (itself). I'm curious about the new kids. (OSP , Palladium...etc.) But one experience I'd like to share is that the high Er materials are susceptible to "background" or "shadow" plating with the e-less finishes. Evidently the material's are loaded with ceramics (or whatnot) that attracts the e-less deposit. Some work fine, some don't. Some e-less chemistries/process lines are better with some materials than others. Maybe run an eval.(?) Good to hear from you. Dave Hoover ______________________________ Reply Separator _________________________________ Subject: Surface Finish Author: [log in to unmask] at SMTPLINK-HADCO Date: 3/6/96 10:04 AM The recent TechNet message on the effect of nickel on high frequency transmission lines was of interest and we are seeking information on the following: We have several fabricators suggesting we replace hot air leveling with and alternative such as electroless nickel-immersion gold, electroless palladium, or just leave the surface bare with an organic surface protector. The boards are Teflon based and dielectric constant can be as high as 10.8. Sounds like nickel is not such a great idea, does anybody have experience or data on palladium or just leaving the surface bare on microwave boards? What is the effect of Palladium? Does the naturally occurring copper oxide on the bare board affect performance? Ted Edwards 602-436-3027 [log in to unmask]