And don't forget nickel, if there is nickel involved. Depending on what
kind of nickel, the resistivity can be 10 to 50 times higher than
copper! I have a nice little article, on page, which explains clearly
the nickel problem at GHz bands.
Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Stadem, Richard
Skickat: den 15 november 2005 20:00
Till: [log in to unmask]
Ämne: Re: [TN] impedance testing
Jim,
I'm not an impedance design guru, but the height of the copper and the
type and thickness of the plating all affect the impedance at GigHz
frequencies due to the skin resistance. It depends on the frequency.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kathy
Sent: Tuesday, November 15, 2005 11:20 AM
To: [log in to unmask]
Subject: Re: [TN] impedance testing
Did you look at the height of the copper on the coupon? (rework)
K Bergman
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jim Henderson
Sent: Tuesday, November 15, 2005 6:28 AM
To: [log in to unmask]
Subject: [TN] impedance testing
Hello,
If there are any impedance testing gurus out there I have a question for
you. We are testing an edge coupled offset strip line coupon. We
modeled the stack up to give us 100 ohms differential. When we test the
coupon we get around 130 ohms. We have done a microsection of the
coupon and modeled the coupon data and Polar says we should have 105
ohms, within tolerance.
We had a 4 panel lot and it is consistent across the board. The coupon
is constructed correctly. My question is, other than what I am seeing
on the microsection should I look for to find the culprit of the high
reading? Any help would be great.
Jim Henderson
Colonial Circuits
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