Guys, I begin to feel schizo,
one says this and another that, and me being slow thinker, not easy. Mark you said this: "The cause of the black pad phenomenon has been found and fixed,
and it has nothing to do with phosphorous!" And you refer to CircuiTree's article by George M. But he pointed that phosphorous was one of mayor concerns, didn't he?: " Major factor Effects on black pad formation are The Structure of Nickel deposit, The Phosphorous Content of the Nickel deposit, The Uniformity of the Nickel and Gold Coatings and finally The Corrosion Rate of the Immersion Gold."
Another one, not Mark, but all of you: Lucent's people have led us back to the central issue, the dark, thin, brittle and elusive shadow, I mean the extremly thin layer between ordinary Ni3Sn4 and the Nickel on the lands. I have asked a lot of people about their experience of compund findings, but no respons yet. What tool do you recommend for examination the layer? EDS? FTIR? XPS? SIMS? or what? Cross sectioning with polishing seems to smear and mislead. Suppose that the BGA falls of, caused by this layer, then you must have the content of the thin layer on one or two parts, either on the BGA balls or on the board lands. If you have these parts in your hand, what would you do then to find out what the brittle P-rich layer is? In my reporting I need add who was the murderer.
Sorry for harping this matter over and over again.
Ingemar
-----Original Message-----
From: Furrow, Robert Gordon (Bob) [mailto:[log in to unmask]]
Sent: den 22 januari 2001 19:07
To: [log in to unmask]
Subject: Re: [TN] Increased Phosphorus in Electroless Ni
I agree with Mark and Dave Fish. The CircuiTree article is excellent and
makes the best case yet that I have seen regarding the cause and elimination
of "Black Pad".
Thanks,
Robert Furrow
New Product Engineering
Lucent Technologies
978-960-3224 [log in to unmask]
> -----Original Message-----
> From: Mark Mazzoli [SMTP:[log in to unmask]]
> Sent: Monday, January 22, 2001 11:58 AM
> To: [log in to unmask]
> Subject: Re: [TN] Increased Phosphorus in Electroless Ni
>
> In case you guys haven't had a chance to see it yet, there's a great
> article in January's issue of CircuiTree regarding ENIG and black pad. It
> states, among other things, that those of you who are dealing with a
> modified general metal finishing bath (as most are) will most likely
> suffer
> some amount of black pad (in essence, regardless of phosphorous
> content). The cause of the black pad phenomenon has been found and fixed,
> and it has nothing to do with phosphorous.
>
> Mark Mazzoli
>
>
>
>
>
>
>
> At 04:42 PM 1/22/01 +0100, you wrote:
> >It's late to say thank you, Georg Milad,
> >but better late than never as they say on Greenland.
> >
> >Someone from Shipley have been here together with the PWB maker
> concerning a
> >superlarge BGA soldering problem. We have learnt a lot since september
> but
> >there remains issues still. What you said below is typical for most
> articles
> >and specs: layer thickness and phosphorous but little about foreign stuff
> >that can appear (even for the best in the game it seems), such as fenoxy,
> >epoxies, glycols, hydrates, carboxyls and a lot more. We made a TOFSIMS
> on
> >some board lands and found SiCH3, C2H3, C3H7, Fe, C5H9, In, SnOH, just to
> >mention an example. And added to that comes the morphologic aspects and
> >about microhardness and boundaries and size and shape of Nickel domes.
> >
> >I thought I had learnt a lot about the BGA soldering, but suddenly I feel
> >how empirical a lot seems to be. "We use to..." or "We think that..".
> >Understand that too, but would like something more in the spec than just
> >thickness and P%.
> >
> >If there is something I can hang up on the wall, and tell people 'this is
> >how a solder pad is being done' I would be vary glad. Guess all other
> >Ericsson groups agree (in silence, of course)
> >Best regards
> >
> >Ingemar Hernefjord
> >Ericsson Microwave Systems
> >
> >PS. Isn't Steph Meschter within Lockheed Martin any more or did he sign
> off?
> >
> >
> >
> >
> >
> >
> >-----Original Message-----
> >From: [log in to unmask] [mailto:[log in to unmask]]
> >Sent: den 6 september 2000 21:04
> >To: [log in to unmask]; [log in to unmask]
> >Cc: [log in to unmask]
> >Subject: Re: [TN] Increased Phosphorus in Electroless Ni
> >
> >
> >Here is my two cents worth on the topic of Electroless Ni , Phosphorous
> >content.
> >Here at Shipley our recommendation for thickness of Electroless Ni is 100
> to
> >
> >250 uins or 2.5 to 6.0 microns. For the gold thickness we recommend 2 -
> 4
> >uins (0.05 - 0.10 microns) as the best thickness to protect the Ni during
> >storage and not to create any Ni defects during processing.
> >As far as Phosphorous content in the Ni deposit we are presently staying
> >with
> >7 -9% P. We have seen data, where High phos (10 - 12%) and Low phos (5
> -7%)
> >
> >gave equally good results, with regards to incidences of "Black Pad".
> >Our tests indicate that High Phos is prone to skip plating and gold
> adhesion
> >
> >failure.
> >The IPC Plating Subcommittee 4-14 will be meeting in Miami, during IPC
> Works
> >
> >2000, at 1:30 to 3:00pm on September the 11th, 2000. The agenda of the
> >meeting is to define an IPC-Standard for Electroless Nickel and Immersion
> >Gold as well as Electroless Gold, as surface finishes widely used in the
> >industry today. Anyone interested in participating is welcome to join the
> >meeting or send his input to me, and I will keep him or her informed of
> the
> >committee progress.
> >George Milad
> >Tech Marketing Mgr.
> >Shipley Ronal Inc
> >Chairman IPC Subcommittee 4 -14
> >
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