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September 2005

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Subject:
From:
"Chezhian, Krishnan" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Chezhian, Krishnan
Date:
Sun, 4 Sep 2005 19:21:15 +0800
Content-Type:
text/plain
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text/plain (101 lines)
The most important thing is the tolerance on the 50 ohms impedance, whether
it is 10% or 5%, because end of the day that is what is going to affect the
functionality of the board. Based on this the PCB manufacturer can
compensate the line widths, dielectric thicknesses etc., as the impedance is
not just a factor of the line width alone, you have the copper height & the
dielectric thickness also that plays an equal role in achieving the
impedance.

Hence the PCB manufacturer has much more manufacturing knowledge, provided
he has been given the correct tolerance & spec. to work with. You cannot tie
the line width & impedance tolerance together, they work hand in hand with
other factors.



Thanks,

Krishnan

SANMINA-SCI

Quality Assurance / NPI Manager

E-mail: [log in to unmask]

Phone (Off): 082-363000 Ext. 1602

Mobile: 012-8888-379



-----Original Message-----
From: sumxp [mailto:[log in to unmask]]
Sent: Sunday, September 04, 2005 2:30 PM
To: [log in to unmask]
Subject: [TN] 5% trace width control_RF



My customer told me that one of the RF pcb need to maintain the 5mils trace

width within 5% tolerance in order to achive 50 ohms impedance.

My pcb maker said they can only control at 20%(copper etching process

capability) trace width tolerance BUT can guarantee that the impedance is

at 50 ohms.

Please comment.Should I take the words of pcb supplier?



rgds

sumxp



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