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March 2005

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Subject:
From:
"Brooks,Bill" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Brooks,Bill
Date:
Thu, 17 Mar 2005 09:30:57 -0800
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text/plain (75 lines)
It depends....
What results are you trying to 'not affect'?

Nickel is lossy at RF frequencies.. The higher the freq. and longer the
transmission line the worse the effect gets if I remember correctly from my
Microwave days...

Does it change the impedance of the line... probably not.

Impedance is a result of the relationship between the dk of the material,
distance of the conductor from it's return path or ground plane and the
width of the transmission line... in a microstrip arrangement.

I don't believe the thickness of the plating is a large enough influence on
the line to change the impedance by any measurable amount.

But lossy RF might be a reason to choose a different surface finish that
doesn't contain nickel. Especially if you are dealing with very low voltage
signals... It's kind of like a trickling stream running along a nice solid
rock bed and then suddenly hitting a huge sand bar... where the water slows
and sinks into the sand... disappearing from view completely...  You don't
want nickel plating on high frequency boards.

If it's not that sort of an application, then you most likely will not have
a problem.

Best regards,


Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com


-----Original Message-----
From: Steve [mailto:[log in to unmask]]
Sent: Wednesday, March 16, 2005 4:00 PM
To: [log in to unmask]
Subject: [TN] Immersion gold

Good afternoon,
A question for the guru's. If I do immersion gold/electroless nickel on top
of an impedance line will it affect the result. Thanks in advance. Steve
Kelly
Sent via BlackBerry
Steve Kelly
PFC Flexible Circuits Limited

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