Hi ,
Many of PCB manufacturers knows this phenomena all along PCB manufacturing :
1 ) "Stubborn " lines in innerlayers , that are reluctant in black oxide .
This is being explained by galvauc action of titanium parts in black oxide tank
2 ) Certain pads and lines in stage of tin-lead ( as etch resist ) on
outerlayers
3 ) Problems in electroless Nickel -immersion Gold . Mainly on the same
problematic areas , that appeared during tin-lead stripping .
There are some theories , but I never had opportunity to get practical
advices on " do - do not do level " .
I am anxious learn more about it .
Regards


 At 18:39 20/10/98 -0400, you wrote:
>     Hi
>        My question is about galvanic action on panels being fabricated.
>     What I am seeing is that certain areas of panels are reacting
>     differently in certain processes. These pads are internally connected
>     to each other. The panel has the normal pattern plate and Ni/Au as
>     well.
>        The pads look different from the surrounding pads and etch at a
>     much higher rate in microetch. I would like to know how common this is
>     and what can be done to eliminate or at least bring it to an
>     acceptable level.
>
>     MikeDoty
>     P.E. Hadco TCE
>
>################################################################
>TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
>################################################################
>To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in the body:
>To subscribe:   SUBSCRIBE TechNet <your full name>
>To unsubscribe:   SIGNOFF TechNet
>################################################################
>Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section
for additional information.
>For technical support contact Hugo Scaramuzza at [log in to unmask] or
847-509-9700 ext.312
>################################################################
>
>
Edward Szpruch
Eltek Ltd - Israel
Tel  972 3 9395050
Fax 972 3 9309581
E-mail :  [log in to unmask]

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################