According to the reported testing in the white paper, there was little insertion loss (db/in) with coating when compared to bare copper up to the test sample limit of around 11GHz. Ron -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer Sent: Friday, August 15, 2014 2:03 PM To: [log in to unmask] Subject: Re: [TN] surface finish for "bare" copper Most RF antenna guys get a little too crazy about this. Up to about 10GHz I see a lot of ENIG used without complaint. If you want to see someone freak out, go ahead and put a conformal coat on the traces! The original fabricator talking about bare copper may have been referring to a chromate anti-tarnish, which is often on the FR4 panels as delivered to the fab. That will hold up for quite a while also, but I don't know if it can be applied post-fabrication. Nickel has poor RF performance. Ag oxidizes and will eventually look ugly, but the performance will probably be good for a long time, particularly with some anti-tarnish applied. Direct Au over copper might be something to consider. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Yuan-chia Joyce Koo Sent: Friday, August 15, 2014 2:43 PM To: [log in to unmask] Subject: Re: [TN] surface finish for "bare" copper (1) you need radar guy (2) my guess would be Ag. just a guess. jk On Aug 15, 2014, at 2:37 PM, Larson, Mark wrote: > Thank you but I guess I should have been more clear, there are no > components and no holes on this board, it is an antenna board, I'm > pretty sure, a couple decades ago perhaps, I had a similar situation > and I ordered bare copper because that's what the engineer said, I got > a call from the fabricator asking, no, make that telling me, we really > didn't want that. Maybe finish isn't the right word, treatment > perhaps, he said the copper could be treated with something that would > prevent oxidizing. I think it was part of their normal process before > applying HASL, but maybe with lead free it is no longer used. > > Maybe I could ask the question, what would you apply to prevent > oxidation yet not affect the performance of the antenna in the several > GigaHertz range.? > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Yuan-chia Joyce > Koo > Sent: Friday, August 15, 2014 1:04 PM > To: [log in to unmask] > Subject: Re: [TN] surface finish for "bare" copper > > agree with steve 100%. It also depend upon your assembly condition: > flux activity, number of reflow, reflow profile, subsequent exposure > to environment.... your design group should pick and choose the right > finishing... not on the MFG floor... my 2 cents. > jk > On Aug 15, 2014, at 1:55 PM, Stephen Gregory wrote: > >> To add to Wayne's input, make sure you call out the right OSP >> depending on the board technology...not all OSP's are the same. >> >> Steve >> >> Sent from my BlackBerry 10 smartphone. >> Original Message >> From: Wayne Thayer >> Sent: Friday, August 15, 2014 11:28 AM >> To: [log in to unmask] >> Reply To: TechNet E-Mail Forum >> Subject: Re: [TN] surface finish for "bare" copper >> >> OSP >> >> -----Original Message----- >> From: TechNet [mailto:[log in to unmask]] On Behalf Of Mark Larson >> Sent: Friday, August 15, 2014 1:12 PM >> To: [log in to unmask] >> Subject: [TN] surface finish for "bare" copper >> >> Hi, >> >> I've got a board that needs bare copper, many years ago I had this as >> well and seem to recall that they can put on some kind of finish in >> the process that does not leave it bare, but does protect it in the >> processing of the board, and consequently does offer some protection >> to the end user. >> Anybody know what >> that is or how I call it out? >> >> -- >> >> >> This email and any attachments are only for use by the intended >> recipient(s) and may contain legally privileged, confidential, >> proprietary or otherwise private information. 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