OSP has more defects when soldering. You can't bake to remove moisture from vendor or stock room lack of control and not resealing. BY the time the SMT processes have finished their two thermal cycles and then hold it up in SMT rework or at the BGA rework areas the OSP preservative is at a minimum. We try to put practices in place where the SMT rework must be done after the last wave or selective solder process but for several reasons they don't.
In the Pb-free soldering process the copper disolution issues and the fact that you can't tell if a location has already been reworked and the whole board is at risk with another component replacement makes the cost and reliability not even close to ENIG.
-------------- Original message --------------
From: Joyce Koo <[log in to unmask]>
> I would take OSP over enig in a heart beat! I guess Doug would jump out with ,
> it depends,
> --------------------------
> Sent using BlackBerry
>
>
> ----- Original Message -----
> From: TechNet
> To: [log in to unmask]
> Sent: Sun Nov 23 08:48:56 2008
> Subject: Re: [TN] black pad
>
> That was a very good explanation. With the advances in process controllers and
> software I would think or expect that the ENIG process is less risky now than
> some 10 years ago when I used to hear about these issues. I know from a
> manufacturing poit I'll take ENIG over OSP any day.
>
> -------------- Original message --------------
> From: Inge
>
> > Can we call it 'Black Pudding' instead, as it is a mess of obscure
> > ingredients?
> > Inge
> >
> >
> > ----- Original Message -----
> > From: "Wenger, George M."
> > To:
> > Sent: Friday, November 21, 2008 10:47 AM
> > Subject: Re: [TN] black pad
> >
> >
> > That is how a lot of the confusion around (I hate t
> >
> > Peter,
> >
> > That is how a lot of the confusion around (I hate the name but I need to
> > use it here) Black Pad started. Creep fatigue cracking, brittle
> > fracture, etc. are recognized failure modes or mechanisms, "Black Pad","
> > Black Line Nickel", etc. are not names of recognized failure modes.
> > They are names of what people see when they look at a failure. They
> > are short cute names that people like to repeat but they don't help to
> > describe what the failure is or what caused it. All I know about "Black
> > Pad" is that it happens with ENIG, it's a low level problem that follows
> > Murphy's Law (i.e., it happens when you least expect it and usually and
> > an inappropriate time), it might be caused by a high P content at the
> > interface, it might be caused by "weak" electroless nickel, it might be
> > caused by cavitation and attack at grain boundaries, it might be cause
> > by too much gold plating attaching the under lying nickel, it might be
> > caused by board shops not controlling the ENIG process properly, etc.
> > There are just too many "might". The data that has been generated by
> > many over the last couple of years certainly shows that control of the
> > plating chemistry is a key to reducing the occurrences of "Black Pad"
> > failures and the number of occurrences has certainly decreased but the
> > failures certainly have not been eliminated. Many of the ENIG failures
> > I've seen over the years are fractures at an interface. Vladimir would
> > certainly not agree with calling all ENIG failures "Black Pad" and I'd
> > agree with him. I'd much rather refer to the ENIG failures as "ENIG
> > Interface Failures" rather than "Black Pad" but that will never happen
> > because "Black Pad" is a cute and short 8 letter name that can even be
> > shorted to two ("BP"). It takes 23 key strokes to type "ENIG Interface
> > failures".
> >
> >
> > Sorry for the long answer but it's Friday and I had an exhausting week.
> >
> > Regards,
> > George
> > George M. Wenger
> > Andrew Wireless Solutions
> > Senior Principle FMA/Reliability Engineer
> > 40 Technology Drive, Warren, NJ 07059
> > (908) 546-4531 (Office) (732) 309-8964 (cell)
> > [log in to unmask]
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Pete Houwen
> > Sent: Friday, November 21, 2008 12:54 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] black pad
> >
> > not to step in a place I don't beloing, between werner and Vladimir, but
> > how
> > about "dark line defect" instead of "black pad"?
> >
> > Similar phenomenon for a different reason.
> >
> > We went through this a while ago, wondering why suddenly boards from a
> > very
> > good ENiG supplier were looking like black pad, all that P on top of the
> > pad.
> > Changing reflow profiles to reduce TAL and max temp, reducing rework
> > cycles
> > made it all go away. All that extra time at temperature just continued
> > the
> > Ni/Sn reaction, leaving P behind. Quantities of Ni in the Sn tipped us
> > off that
> > we weren't starting out with black pad, but we were ending up with it.
> >
> > I do get why people don't like ENiG, but we've done very well with it by
> > making
> > sure we use good suppliers.
> >
> > Pete
> >
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