[SI-LIST] Re: Embedded uStrip - double check me
- From: kfrobinson@xxxxxxxxxx
- To: <si-list@xxxxxxxxxxxxx>
- Date: Thu, 6 Nov 2003 09:50:56 -0700
Bill,
A couple things to keep in mind. Many tools model plating in such a way =
as to make the trace thicker and wider than its original size =
(electroless) when in fact your plating maybe done in such a way that it =
is only on top of the trace (electro) making it thicker only. You may =
have noticed making a trace thicker (1/2oz to 1oz) has only a small =
effect on impedance. So, if you ignore your plating I bet you will =
notice your numbers come in line with the fabrication house numbers. =
Another factor that people need to keep in mind is that many of us have =
always assumed that 1/2 oz copper is .0007" thick. Well it has come to =
my attention that core manufactures have decided to save themselves a =
buck of two and are depositing copper at the low end of the spec =
thickness. I have had several samples measured and it is almost always =
.00063" thick for half oz copper.
Ken Robinson
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of bdempsey85
Sent: Wednesday, November 05, 2003 5:40 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Embedded uStrip - double check me
I would like a double check on my coated uStrip impedance calculations.
I am getting feedback from my PCB fabricator that my numbers are >10%
off.
Here are the parameters:
5 mil wide trace, 0.5 foil with add'l 1oz plating (approx 2.1 mils
thickness)
4 mil trace to plane, Er ~ 4.3
LPI soldermask ~ 0.8 mils thick
I compute 51 ohms...how about you?
Thanks,
Bill
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at: =20
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages=20
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
