It appears that ENIG gold is extremely thin (2 - 8 microinches), and if so does not cause a solderability problem.
-- Tom, N5EG On Thu, Feb 22, 2018 at 3:18 PM, Mark Goldberg <[email protected]> wrote: > My reading of IPC J-STD-001F Paragraph 4.5 says that the gold embrittlement > issue does not apply to ENIG or ENEPIG. Paragraph 4.5.1 does say other gold > shall be removed so there won't be solder embrittlement. > > Is that still correct? > > The issue with ENIG and RF is interesting. I have not heard that before but > I can find lots of info on the subject. I do not remember seeing ENIG on > microstrip boards. > > Regards, > > Mark > > > On Thu, Feb 22, 2018 at 2:33 PM, Tom McDermott <[email protected]> wrote: > > > In general it's bad practice to gold plate SMT solder pads. The reason > is > > that proper SMT soldering utilizes a very small amount of solder and the > > gold plating > > will partially dissolve into the molten solder. Because of the small > amount > > of > > solder, the percentage of gold will be high enough to embrittle the > solder > > joint, > > and it will have a high probability of failure. > > > > Hand soldering can apply a large enough amount of solder that the > > percentage > > of gold in the joint is relatively small and the problem is avoided. > > > > -- Tom, N5EG > > > > > > > > > > On Thu, Feb 22, 2018 at 12:29 PM, Leo Bodnar <[email protected]> wrote: > > > > > Here is ENIG fact that is not widely known at the moment but which some > > > might find useful. > > > > > > I could not understand why I get better TDR and insertion loss results > > > from solder-mask covered microstrip transmission lines than from > > otherwise > > > identical microstrips on the same substrate with soldermask removed > and, > > > therefore, covered with ENIG. > > > > > > Gold can't be bad, right? As it turns out, even gold coin has two sides > > to > > > it. > > > > > > I have found that Shlepnev and McMorrow conducted extensive research > and > > > published data, some of which is presented here > > http://www.simberian.com/ > > > Presentations/NickelCharacterizationPresentation_emc2011.pdf > > > > > > In essence, it's not the "G" that is the problem - it is the "N". > > > Immersion Gold layer is not thick enough to contain whole of the skin > > > effect layer (even towards 100GHz) and as signal frequency increases > most > > > of the signal ends up travelling through Nickel. > > > As Shlepnev commented "Nickel is the most mysterious metal in > > > electronics." It has significant effect on insertion loss and risetime > > > degradation. "Significant effect" is posh for "bad." > > > > > > Some mass PCB manufacturers have been known to apply ENIG before > > > soldermasking. This causes even more high speed/frequency problems > > because > > > all of the copper on the outside layers will have Nickel over it - > > exposed > > > or not. > > > > > > Probably not a problem for majority of ENIG users but could cause a > > > headache or two for unsuspecting. > > > > > > Leo > > > > > > > Date: Thu, 22 Feb 2018 19:02:25 +0000 > > > > From: Mark Sims <[email protected]> > > > > > > > > Yes, have the board done with ENIG gold. It typically adds around > $15 > > > per run of boards. I do all my boards with ENIG gold... if for no > other > > > reason than the gold color makes it very easy to determine when your > > solder > > > paste properly covers the pads. > > > > > > > > And, as Charles mentioned, the quality and thickness of the gold can > > > vary depending upon the board house. I have used gojgo.com for a lot > of > > > boards. They do very good, quick work, are well priced, and they seem > > to > > > have the best gold finish. > > > > > > > > Hard gold finish is VERY expensive these days. I've been quoted > $250+ > > > for setup charges and per-board costs of over $25. > > > > > > _______________________________________________ > > > time-nuts mailing list -- [email protected] > > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > > mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to https://www.febo.com/cgi-bin/m > > ailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
