Hi Craig - yea, something just doesn't look right. If you have the
resources, I would conduct an XRF plating thickness survey on the boards
where you can and then a cross section too. The plating appearance after
reflow is not typical of what I am used to observing.

Dave

On Thu, Aug 27, 2015 at 2:27 PM, Craig Sullivan <[log in to unmask]>
wrote:

> Attached are pics. Sent to Steve Gregory for posting, directly to Dean and
> David.
>
> Pic 0 is where a trim pot lifted right off, 1 minute ago. It appears to be
> a layer of Ni left on the pad.
> Pic 1 is a circuit where a trim pot fell off at the slightest touch.
> Again, looks like a layer of Nickel left on the pad. It's gray in color
> compared to the gold PTH.
> Pic 2 is what I am seeing on PTHs after we reflow these things.
>
> It only appears after the reflow. I have not seen it before.
> Also, I have seen no discernible difference in plating colors.
>
> Craig Sullivan
> Manufacturing Engineer / IT Administrator
> Phone:  (607) 266-0480 x115
> Fax:  (607) 266-0482
> Email: [log in to unmask]
> Web:  www.mplinc.com
>
> MPL, Inc.
> 41 Dutch Mill Road  |  Ithaca  |  NY  |  14850
>  Please consider the environment before printing this e-mail.
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
> Sent: Thursday, August 27, 2015 3:06 PM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG coating durability
>
> Sorry about the lack of continuity in my emails. But the reason I asked
> about the orange pads is because through the years I have noticed that
> sometimes if the immersion gold layer is too thin, say from 1 to 3 uinches,
> the nickel layer can begin to oxidize underneath as Dave described, and if
> the boards are older, the nickel can oxidize so badly that it does not even
> provide a barrier to the copper underneath the nickel. What happens then is
> that the copper can reach the gold, and it reacts right up on the surface
> and it shows up as orange pads interspersed amongst the gold pads I can see
> (at 20X magnification).
> I have seen this (myself) like 3 or 4 times in the past 15 years, and I
> have found that it is a sure indicator of either nickel skips in the
> plating, or the ability of the nickel to completely oxidize and allow the
> copper through (thin nickel), or insufficient gold, all of which can lead
> to the oxidized pads and solderability issues in older ENIG PWBs. If you
> can see any evidence of this on PWBs not yet soldered, it is evidence of
> absence of either nickel or gold, or both. No fabricator can dispute it.
> Evidence of absence is not absence of evidence.
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
> Sent: Thursday, August 27, 2015 1:27 PM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG coating durability
>
> No problem. Send pictures of the pad surface after the parts were removed
> also, if you can. That can be very revealing.
> One more question. On the bare PWBs not yet processed, are there pads that
> are a little bit more "orange" than gold in appearance?
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Craig Sullivan
> Sent: Thursday, August 27, 2015 1:14 PM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG coating durability
>
> Sections and SEM are forthcoming.
> I agree with both of you.
>
> Richard: Apologies for my terminology. Yes... we assembled bare PCBs into
> CCAs and the problems appeared at this process.
>
> Craig Sullivan
> Manufacturing Engineer / IT Administrator
> Phone:  (607) 266-0480 x115
> Fax:  (607) 266-0482
> Email: [log in to unmask]
> Web:  www.mplinc.com
>
> MPL, Inc.
> 41 Dutch Mill Road  |  Ithaca  |  NY  |  14850 P Please consider the
> environment before printing this e-mail.
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
> Sent: Thursday, August 27, 2015 2:06 PM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG coating durability
>
> Hi Richard - good info. The issue Craig described could also just be
> oxidation of the nickel thus making solderability near zero and then the
> parts just "fall off".
>
> Dave
>
> On Thu, Aug 27, 2015 at 9:50 AM, Stadem, Richard D. <
> [log in to unmask]> wrote:
>
> > I seldom see issues with ENIG-finished PWBs even after 5 years or
> > longer, provided the ENIG finish was properly applied in the first
> > place and the boards were stored properly during that time. ENIG, when
> > done properly, is a very, very durable finish. The 4-5 uinches of gold
> > will protect the underlying nickel very well, and that is what you
> > actually solder to, not the gold.
> > However, when problems such as those you are describing show up after
> > soldering, it is a very strong indicator of Black Pad. If the ENIG is
> > not plated properly and the immersion gold is not applied just right,
> > after soldering the components you can send perfectly robust CCAs into
> > the field, and in a few months the components can begin literally
> > falling off the board. It sounds like what you are seeing is Black Pad.
> > Just google up ENIG and Black Pad and you will see examples of the
> > cratering and appearance of the pads, and compare them with the
> > pictures of your own.
> > Just about every time, the pictures are very similar.
> > Quite often, much older ENIG PWBs from one vendor solder much better
> > than those of another vendor that were fabricated and plated two weeks
> > ago. This is due to the plating process controls (or lack thereof) at
> > the fabricator, not the age of the plated PWB itself.
> > Your email is a little bit confusing; when you state " PCBs just over
> > a year old are showing signs of oxidation after processing, components
> > can be flicked off with ease." Printed circuit boards (PCBs) are bare
> > boards with no components assembled, whereas PCBs with components
> > assembled are known as CCAs (Circuit Card Assemblies).
> > If you mean that after the PCB is processed to solder components, and
> > immediately after that the parts fall off, yes, that is a sign of one
> > type of Black Pad, but it can also show up months later on assemblies
> > that were perfectly robust immediately after soldering.
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Craig Sullivan
> > Sent: Thursday, August 27, 2015 8:03 AM
> > To: [log in to unmask]
> > Subject: [TN] ENIG coating durability
> >
> > J-STD-003 and IPC-4552 basically state the ENIG should meet category 3
> > (>6 months storage).
> >
> > My question is, what is the storage threshold for ENIG after the 6
> months?
> > 1 year, 2 years?
> >
> > What length of time should we conceivably expect to be able to store
> > an ENIG board before seeing issues?
> >
> >
> >
> > Scenario: PCBs just over a year old are showing signs of oxidation
> > after processing, components can be flicked off with ease. The Cu and
> > Ni (if any
> > left) on a PTH look horrendous after processing. Here's a kicker,
> > these boards are date code 3414, but date code 3514 appears to be ok
> > and solders fine, and date code 3114 shows a very low and random case
> > of the oxidation/solderability issue.
> >
> >
> >
> > All PCBs stored in the same environment/manner
> >
> >
> >
> > Craig Sullivan
> >
> > Manufacturing Engineer / IT Administrator
> >
> > Phone:  (607) 266-0480 x115
> >
> > Fax:  (607) 266-0482
> >
> > Email:  <mailto:[log in to unmask]> [log in to unmask]
> >
> > Web:   <http://www.mplinc.com/> www.mplinc.com
> >
> >
> >
> > MPL, Inc.
> >
> > 41 Dutch Mill Road  |  Ithaca  |  NY  |  14850
> >
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> >
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