Guenter,

Black Pad can not be identified visually, you need to do surface analysis.
What you will see is obvious dewetting.  Since the nickel appears in varying
shades of gray, it is commonly called "black pad".  However, dewetting is
caused by more things than just what is traditionally associated with "black
pad" (hyper corrosion of the nickel).

Be careful of red herrings.  I have been asked to verify black pad on
numerous occasions (and it can't be visually verified), only to identify
gold remaining on the pad.  The pad dewetted and appeared black because
whatever contamination was covering the pad had apparently carburized.  I
try explaining that the gold will dissolve within a tenth of a second of
soldering so there must be something between the pad and solder, but the
glassy stares of the onlookers leads me to believe that most people don't
understand what I'm talking about.  I think you do.

Kind Regards

Ryan Grant
Advanced Technology Engineer
MCMS
(208) 898-1145
[log in to unmask]




> -----Original Message-----
> From: Guenter Grossmann [SMTP:[log in to unmask]]
> Sent: Friday, May 18, 2001 1:48 AM
> To:   [log in to unmask]
> Subject:      [TN] Black Pad
>
> Quite a while ago there was a discussion in TechNet about Black Pad. I
> read some articles too, but what I am missing is a picture or two or so
> how Black pad looks like ( sure it's more than just black ).
>
> Have a great day
>
> Guenter
>
> Guenter Grossmann
>
> Swiss Federal Institute for Materials Testing and Research EMPA
> Centre for Reliability
> 8600 Duebendorf
> Switzerland
>
> Phone: xx41 1 823 4279
> Fax :      xx41 1823 4054
> mail:     [log in to unmask]
>
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