What Frequency? Since they are using Duroid, I think it is save to assume it is for RF. Nickel is a barrier to RF. Depending on the Frequency, Power level and loss acceptance, ENIG may be acceptable but will not give as good as a performance as HASL. Unfortunately many RF designs require enclosing the circuit to minimize leakage and HASL is not flat enough to seal against well. You might suggest IAg as you will get both flat surface and less loss due to finish (RF skin effect). I am not sure if the Dk of the finish metals will have any real effect, but am certain that best RF performance does not come with Nickel based finishes. Call me if you want to discuss further. Hope it helps, FNK Frank N Kimmey CID+ Principal PCB Designer Powerwave Technologies Inc Office 916-941-3159 Fax 916-941-3195 Cellular 916-670-0645 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Kathy Sent: Tuesday, November 29, 2005 3:01 PM To: [log in to unmask] Subject: [TN] I am posting this ? for a colleague: "We are fabricating some boards for a customer that will be 1 oz of copper on Duroid 6010. They are considering two surface finishes: HASL (Hot Air Levelled Solder) and 150u" Nickel under 5-10 u" Gold. The question they are asking is as follows: What are the dielectric properities of the Nickel/Gold finish vs. those of the HASL finish. Does anyone know the answer? I figured that the insulating material (the Duriod) and the conductor thickness (copper) would have the largest influence on dielectric performance and that the surface finish would have a negligible impact on performance. Is this true?" Thanks! --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------