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January 2001

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Subject:
From:
Mark Mazzoli <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 23 Jan 2001 08:30:41 -0800
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Ingemer,

Actually, I was referring to the article in the January 2001 issue by Mike
Walsh (Electroless Nickel, Immersion Gold, Black Pad).  It shows
comparisons between modified general metal finishing baths and a bath
formulated for PCB's.  Rather than put his findings into my own words I'd
recommend reading it.

Mark

At 12:51 PM 1/23/01 +0100, you wrote:
>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

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