Hi Vladimir,
No, I would not agree that the same phenomenological situation should get a different name, just because it is caused by a different set of inputs. [The solder joint with a fatigue crack is a fatigue failure whether the cause is thermo-mechanical loading or purely mechanical loading].
'Brittle fracture' as well as 'de-wetting' have already well understood meanings different from BP. However, brittle fracture includes BP as well as other brittle fractures resulting from other problems.
I would not call any problems resulting from electroless Ni plating with no or insufficient P 'Black Pad'--I have not seen a special name for tis situation.
Having a limited number of pads affected is pretty typical of 'Black Pad'; one requirement for BP is the presence of a NiSn-IMC layer. Typical BP does not show corrosion/cavitation.
Werner
-----Original Message-----
From: Igoshev, Vladimir <[log in to unmask]>
To: [log in to unmask]; [log in to unmask]
Sent: Thu, 20 Nov 2008 10:31 pm
Subject: Re: [TN] black pad
Good. And since we have agreed that different thenomenon (root causes) can cause almost identical appearance (Black), then would it be logical to use a different name for each of them (Black Pad; Brittle Fracture: Dewetting, etc.).
Just to give an example, a few days ago I came accross two different problems with ENIG and I still don't know what had caused them (to be exact, I suspect the root cause in both cases is in the plating process
).
The reason I mentioned about them is that both could have been easily (and wrongly) called Black Pad, as the pads were dark (as usual after joint is broken or not formed. However, in one case only limited numer of pads exhibited the problem, and the layer of E-Ni was not corroded/cavitated (ruling out Black Pad, as I understand it). In the second case, E-Ni had NO phosphorus in it (at least I couldn't detect it with EDS) and I know it was supposed to be Ni-P, not Ni-B.
U don't even know how to call that case, but definitely not Black Pad :-)
Regards,
Vladimir
----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Thu Nov 20 18:17:42 2008
Subject: Re: [TN] black pad
Agreed, the prescription for the fix will be different.
Werner
-----Original Message-----
From: Igoshev, Vladimir <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 20 Nov 2008 5:52 pm
Subject: Re: [TN] black pad
Hi Werner,
I completely agree on what we disagree on :-)
I think that the same appearnce can (and is in that particuar case) be caused by
completely different phenomena, therefore the recepie to fix/avoid it will be
different.
Regards,
Vladimir
----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Thu Nov 20 17:28:06 2008
Subject: Re: [TN] b
lack pad
Hi Vladimir,
That is where we disagree--the definition of 'Black Pad.'
I define it as the phenomenon root cause regardless of what caused it--that is
not to say that who caused it is unimportant.
Werner
-----Original Message-----
From: Igoshev, Vladimir <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 20 Nov 2008 5:20 pm
Subject: RE: [TN] black pad
Hi Werner,
I should have referred to your exact phrase,
so you wouldn’t have to correct me J
As far as the definition of BP is
concerned, then I still prefer to define it as a manufacturing defect, which
has nothing to do with the assembly process.
The presence of thicker P-enriched layer
isn’t a good thing but in true cases of BP it’s normal
(thickn
ess-wise) but the joints has almost zero strength.
Regards,
Vladimir
From:
[log in to unmask] [mailto:[log in to unmask]]
Sent: Thursday, November 20, 2008
5:06 PM
To: [log in to unmask]; Igoshev,
Vladimir
Subject: Re: [TN] black pad
Hi Vladimir,
I did not s
ay 'excessive temperature'-- I said 'the more you expose
an ENIG layer to soldering temperatures'--that means multiple or lengthy
exposures.
If you define 'Black Pad' as the presence of P at the Ni/NiSn-IMC interlayer to
a degree significantly weakening that interface, then you can arrive at that
condition by
multiple paths.
One is faulty manufacturing, the other is excessive Ni-dissolution--of course,
these can work in combination.
Werner
-----Original
Message-----
From: Igoshev, Vladimir <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 20 Nov 2008 4:45 pm
Subject: Re: [TN] black pad
Well, with all due respect I would have to disagree with you Werner (not
for the first time :-)). I wouldn't associate Black Pad with excessive
soldering temperature. It's rather a board manufacturing related issue.
Regards,
Vladimir
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Thursday, November 20, 2008 4:38 PM
0A
To: [log in to unmask]
Subject: Re: [TN] black pad
=0
A
The more you expose an ENIG layer to soldering temperatures, the more
Ni dissolves leaving more P at the layer between the Ni and the
NiSn-IMC. The more? P the weaker this interface, leading to 'Black Pad'
Werner
-----Original Message-----
From: henry rekers <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 20 Nov 2008 3:41 pm
Subject: Re: [TN] black pad
=0
A
Can you give me any examples of black pad being caused by anything other
than a
"bad board"? ie.? Is there anything in processing "perfect board" that
would
cause a de-wet condition that indicates black pad??? I guess where I'm
going is,
can
this be anything other than a supplier issue?
--- On Thu, 11/20/08, Werner Engelmaier /* <[log in to unmask]> wrote:
From: Werner Engelmaier /* <[log in to unmask]>
Subject: Re: [TN] black pad
To: [log in to unmask]
Received: Thursday, November 20, 2008, 1:26 PM
Hi 'rekers,'
You canno
t broad-brush like this. Some FAB houses do quite well, others
not.
ENIG, from various sources and at various conditions, has shown nickel
corrosion or high phosphide concentrations. The underlying reasons for
these are
different, actually diametrically opposed. Some are the fault of the FAB
house
others not.
Werner
-----Original Message-----
From: henry rekers <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 20 Nov 2008 12:45 pm
=0
A
Subject: [TN] black pad
Anybody out there experiencing mass dewetting issues from North American
board
shops?
?
From what I understand primary causes for dewetting (assuming the
reflow/wave
profile is bang on) is all on the board, ie nickel corrosion,
degeneration of
the nickel, or outgassing of the nickel/copper.? (I'm talking enig
here.)
?
Anybody?
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