If you email the gerber or Valor step of the coupon I can review it and
give you some feedback.



Jeffrey Bush

Director, Quality Assurance and Technical Support



                          76 Technology Drive - POB 1890

                             Brattleboro, Vermont 05302-1890

                                Tel. 802.257.4571.21 Fax. 802.257.0011

                                    [log in to unmask]

                                          http://www.vtcircuits.com  

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jim Henderson
Sent: Tuesday, November 15, 2005 9:28 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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