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 > > > > P Please consider the environment before printing this e-mail. > > > > > > > > _____ > > > > Confidentiality Notice: > > This e-mail contains privileged and confidential information which is > > the property of MPL Incorporated, intended only for the use of the > > intended recipient(s). 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