Karen, Great paper, thank you. Not a large change for simple SMT paste flux residues but I can see issues if the entire board, or section, is covered with the flux. Thanks, Bob K. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Karen Tellefsen Sent: Wednesday, June 27, 2012 7:25 PM To: [log in to unmask] Subject: Re: [TN] High frequency, ENIG and no-clean Sort of. We saw a shift in the resonance frequency for T-resonators with and without no-clean solder paste flux residues. Relating this to dielectric constant is not easy for the reasons given by Frank M. Duffy et al, RF Characterisation of no-clean solder flux residues International symposium on microelectronics, Baltimore MD , 2001 , vol. 4587, pp. 138-143 Karen Tellefsen - Electrical Testing Alpha / 109 Corporate Blvd./ S. Plainfield, NJ 07080 [log in to unmask] 908-791-3069 From: Robert Kondner <[log in to unmask]> To: <[log in to unmask]>, Date: 06/27/2012 03:06 PM Subject: Re: [TN] High frequency, ENIG and no-clean Sent by: TechNet <[log in to unmask]> Frank, I was happy to hear your personal attitude towards No Clean, but I was hoping for something a little more analytical. You mention the coating can and does act like a dielectric, but what value? Is it close to FR4? Air? If someone takes a network analyzer can they detect the presence of a glob of no clean left on a joint? I don't know, I am simply asking. The high Z application you mention where a no clean residue affected performance, that is not a RF and dielectric issue, that is a conductivity issue. It is these "Soft and Fuzzy" personal observations that really don't count in my book. Like Joe Friday: "Just the Facts Ma'ma". Anything else is, well, potential hogwash. Thanks, Bob K. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Frank Kimmey Sent: Wednesday, June 27, 2012 2:06 PM To: [log in to unmask] Subject: Re: [TN] High frequency, ENIG and no-clean Okay Bob, let's discuss what happens with no-clean and RF. No-clean leaves residue, commonly contaminants are contained in an inert (after cure) material. This coating can and does act as a dielectric. As we know, dielectric changes impedance and impedance is what RF is all about. Now, where the real issue comes to play is that the residue left by no-clean is not a consistent thickness and dielectric thickness is what has the largest effect on RF impedance. So if no-clean causes impedance changes/mismatch in some areas of the RF path and not others then performance is adversely affected. My first experience 20 years ago with this phenomenon was with high impedance analog terraces were we saw a marked degradation in performance of analog sensor circuits due to no-clean. Now with higher powered RF circuits we see that any time loss is critical (the key here is loss not power so it doesn't really matter how large the signal is) no-clean does bad things to our signals. Some of us use ENIG in our RF designs (I like the noble metal if I need to leave exposed), others like IAg (silver is a great conductor) and others use ISn (Tin works if you don't mind a whisker risk). Bottom line is for best performance you need consistency and with no-clean you don't get it as the left overs are not consistent across the circuit and that DOES cause signal degradation. At least that's what I have observed. FNK Frank N Kimmey CID+ Manager - PCB Design Powerwave Technologies Inc. Mobile - 916-670-0645 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner Sent: Wednesday, June 27, 2012 10:37 AM To: [log in to unmask] Subject: Re: [TN] High frequency, ENIG and no-clean Richard, I absolutely believe the ENIG issue is important. It was the No Clean part of the question I was wondering about. Bob K. PS: I am about to hit send! :-) -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Wednesday, June 27, 2012 1:25 PM To: [log in to unmask] Subject: Re: [TN] High frequency, ENIG and no-clean Sorry about that, "send" button was hit before I finished. Ioan's original question was: Can anybody point me towards papers talking about the influence of no-clean soldering and ENIG on high frequency performance? - With ENIG, your final surface layer is nickel, not gold. - For very high frequency signals (generally considered to be above 1 gigahertz), electrical conductance takes place on the surface of the trace (the nickel-plated part) due to the Hall or "skin" effect. - Nickel's conductivity at frequencies above 1 Ghz is somewhat reduced, compared with copper or gold. This is considered a "lossy" circuit performance. There are many papers on this subject, including some from Werner Engelmaier. - I did not address losses through flux residues, only those regarding signal loss in Db through nickel. But again, signal crosstalk and loss through flux residue is well-documented. I can assure you, Bob, it is NOT "hogwash". -----Original Message----- From: Stadem, Richard D. Sent: Wednesday, June 27, 2012 12:10 PM To: [log in to unmask] Subject: RE: [TN] High frequency, ENIG and no-clean Go back to Ioan's original question: -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner Sent: Wednesday, June 27, 2012 11:46 AM To: [log in to unmask] Subject: Re: [TN] High frequency, ENIG and no-clean Hi, I have often wondered if this No-Clean Flux vs. RF issue was real or hog wash so I tried to look at these links. The first link must have changed pages, can anyone identify the new link or subject description. The second link was about the Ni plating vs. RF. I saw no reference to flux or no clean. Did I miss something in my quick scan? Thanks, Bob K. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Wednesday, June 27, 2012 11:31 AM To: [log in to unmask] Subject: Re: [TN] High frequency, ENIG and no-clean http://www.taconic-add.com/mwg-internal/de5fs23hu73ds/progress?id=rG3E1oaXW1 http://athena-gatech.org/papers/staiculescu13.pdf There are many more. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea Sent: Wednesday, June 27, 2012 9:00 AM To: [log in to unmask] Subject: [TN] High frequency, ENIG and no-clean Dear Technos, Can anybody point me towards papers talking about the influence of no-clean soldering and ENIG on high frequency performance? 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