[SI-LIST] Re: Loss Tangent of Solder Mask
- From: "Jim DeLap" <jpd_ansoft@xxxxxxxxx>
- To: <ray_waugh@xxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Fri, 7 Mar 2003 11:10:19 -0500
Ray,
I disagree with your assumption below that the fields above the line are =
"so
weak." The fields above the line are dependent upon the dielectric =
material
above and below the line. The fields will concentrate in regions of high
dielectric constant. Therefore, for lower permittivities such as those =
in
FR4, you may have a significant portion of the fields propagating in the =
air
or soldermask. Now for high permittivity materials such as ceramics and =
Si
or GaAs, your statement is fairly valid since the er is so high, most of =
the
fields are constrained to the dielectric rather than the air above.
-Jim DeLap
Ansoft Corporation
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On
Behalf Of ray_waugh@xxxxxxxxxxx
Sent: Thursday, March 06, 2003 7:03 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Loss Tangent of Solder Mask
Michael...
Unless you are forming a transmission line using a conductor over a =
ground
plane with solder mask as the dielectric, it does not much matter. If =
you
are concerned about solder mask over the top of a microstrip line (for
example), the e-fields above the line is so weak that you'll never be =
able
to tell (by measurement) if there is solder mask there or not. We =
commonly
use solder mask on our 2 GHz CDMA test boards (on top of microstrip or
coplanar waveguide lines) and it has no effect whatsoever.
Ray
Raymond W. Waugh
Agilent Technologies
-----Original Message-----
From: Chan, Michael (Eng Hou) [mailto:Michael.Chan@xxxxxx]
Sent: Thursday, March 06, 2003 9:23 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Loss Tangent of Solder Mask
Hi:
Anybody has any idea what is the loss tangent of solder mask? =
Thanks.
=20
=20
Regards,
Michael Chan
H-P Corp.
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