Phillip,

In the early days of the ENIG "Black Pad" there was some evidence generated by a PCB vendor that indicated one reason there were random "Black Pad" failures was because of local potential  (i.e., "floating voltage") differences.  it was even suggested that there were two ways to prevent "floating voltages"; either tie every node on a board to the same potential but that means you would need to remove the shorts before you could use the boards or even worst the second option was to make every pad on the board an isolated trace but that would mean there would be no connecting circuitry.

Regards,
George

George M. Wenger (908)-546-4531 
Reliability / FMA Engineer
Base Station and Subsystems Group
Andrew Corporation,  40 Technology Drive, Warren, NJ 07059
[log in to unmask]



-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Anslow, Phillip
Sent: Tuesday, August 24, 2004 9:37 AM
To: [log in to unmask]
Subject: [TN] ENIG and Electrical Test


Has anyone heard of "floating voltages" on certain nets of a C-I-C cored
power board affecting the ENIG process?
It's not Friday, it's not April but I'm wondering if anyone has had
experience of this phenomenon from a PCB fabricator before - of have we
stumbled across an answer for lead-free batteries?
TIA - Phil.

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