We've coated some military ant. with Parylene N before.
Lloyd Duso
Diamond-MT
Plant Manager
(814) 535-3505
www.Diamond-mt.com
On Fri, Aug 15, 2014 at 3:36 PM, Larson, Mark <[log in to unmask]>
wrote:
> Mechanical designers spec Zinc chromate on aluminum to prevent oxidation
> when you want "bare" metal
> But you've probably heard of hexavalent chromium, nasty stuff, irridite
> or non-hexavalent chromium is what they spec now
>
> Anybody hear of "Benzotriazole"?
>
>
> -----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?
> >>
> >> --
> >>
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