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 <marklgoldb...@gmail.com>
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 <tom.n...@gmail.com> 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 <l...@leobodnar.com> 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 <hol...@hotmail.com>
> > > >
> > > > 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.
> > >
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