[SI-LIST] Re: Stripline Propagation Velocity
- From: r.satrom@xxxxxxxxxxxxx
- To: si-list@xxxxxxxxxxxxx
- Date: Thu, 16 Aug 2012 13:03:23 -0500
Hello All-
Thanks for your feedback. The resin content is the most likely
contributor to the difference in results. I will look into it with our
manufacturing team.
I'd prefer not to disclose which board materials, but in order to get an
idea of the results, here are the values that I've measured/calculated
with the material names removed:
Board #1 4mil (er=3.43; vp=156.8 ps/in), 8mil (er=3.80; vp= 165.1
ps/in)
Board #2 4mil (er=3.71; vp=163.1 ps/in), 8mil (er=3.86; vp= 166.3
ps/in)
Board #3 4mil (er=3.61; vp=160.9 ps/in), 8mil (er=3.87; vp= 166.5
ps/in)
Board #4 4mil (er=3.63; vp=161.4 ps/in), 8mil (er=3.81; vp= 165.2
ps/in)
Board #5 4mil (er=3.27; vp=153.1 ps/in), 8mil (er=3.44; vp= 157.1
ps/in)
Board #6 4mil (er=4.08; vp=171.1 ps/in), 8mil (er=3.96; vp= 168.6
ps/in).
In summary, there is a change of speed of between -3ps/in and +8ps/in, and
a change in dielectric of between -0.12 and +0.37.
Regards,
Ryan
----------------------------------------------------------------------------
Ryan Satrom | Signal Integrity Engineer
Phone: 651-407-7711 | Fax: 651-407-7290
r.satrom@xxxxxxxxxxxxx | Skype: satromium
Multitest Contactor Division
4444 Centerville Road, Suite 105
Saint Paul, MN, USA, 55127
http://www.multitest.com
From:
Kirby Goulet <kgoulet@xxxxxxxx>
To:
"ryan.satrom@xxxxxxxxxxx" <ryan.satrom@xxxxxxxxxxx>,
"si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
Date:
08/16/2012 10:49 AM
Subject:
[SI-LIST] Re: Stripline Propagation Velocity
Sent by:
si-list-bounce@xxxxxxxxxxxxx
Hi Ryan
Here is a report from a impedance calculator. One case with 4mil cores,
and two cases with 8mil cores (with two trace widths). All cases the cores
are Er 4.2 and the resin at 3.6. This includes a trapezoidal
cross-section.
The propagation velocities changed. Not sure if in the amount you
expected.
-------------------------------
2D Impedance Calculator Program
Version 0.2.1.88
Time: Thu Aug 16 11:36:28 2012
GPL Version 2.0
-------------------------------
Simulation pix map 140 pixels high by 700 pixels wide.
295024 bytes allocated for bmp.
Simulation pix map 120 pixels high by 700 pixels wide.
253024 bytes allocated for bmp.
INPUT PARAMETERS:
Layer Thick Specifications
Copper Plane Top 1.30 Opening w=0.0 offset=0.0
Laminate Layer 1 4.00 Resin Content 64.3% 3.2-6.0
Signal Layer 1 1.35 Width=4.0 Etchback=0.50
Laminate Layer 2 4.00 Resin Content 64.3% 3.2-6.0
Copper Plane Bottom 1.30 Opening w=0.0 offset=0.0
Layer Thick Er Loss Tangent
Copper Plane Top 1.30 3.20
Laminate Layer 1 4.00 4.20 0.00120
Signal Layer 1 1.35 3.60 0.00120
Laminate Layer 2 4.00 4.20 0.00120
Copper Plane Bottom 1.30 3.20
Rdc_trace_1= 143.64 milliohms/in 20C
DC resistance by pixel count:
Rdc_trace_1= 139.650 milliohm/in.
C = 3.930 pF/in L = 7.500 nH/in.
Er = 4.106 Loss_tan = 0.00120
Zo = 43.685 Ohms Delay = 171.675 ps/in.
Simulation pix map 200 pixels high by 700 pixels wide.
421024 bytes allocated for bmp.
INPUT PARAMETERS:
Layer Thick Specifications
Copper Plane Top 1.30 Opening w=0.0 offset=0.0
Laminate Layer 1 8.00 Resin Content 64.3% 3.2-6.0
Signal Layer 1 1.35 Width=4.0 Etchback=0.50
Laminate Layer 2 8.00 Resin Content 64.3% 3.2-6.0
Copper Plane Bottom 1.30 Opening w=0.0 offset=0.0
Layer Thick Er Loss Tangent
Copper Plane Top 1.30 3.20
Laminate Layer 1 8.00 4.20 0.00120
Signal Layer 1 1.35 3.60 0.00120
Laminate Layer 2 8.00 4.20 0.00120
Copper Plane Bottom 1.30 3.20
Rdc_trace_1= 143.64 milliohms/in 20C
DC resistance by pixel count:
Rdc_trace_1= 139.650 milliohm/in.
C = 2.807 pF/in L = 10.527 nH/in.
Er = 4.116 Loss_tan = 0.00120
Zo = 61.240 Ohms Delay = 171.895 ps/in.
Log file save name:
mdtlc_12071641904.txt
Log file save name:
mdtlc_12071641924.txt
Simulation pix map 200 pixels high by 900 pixels wide.
541024 bytes allocated for bmp.
INPUT PARAMETERS:
Layer Thick Specifications
Copper Plane Top 1.30 Opening w=0.0 offset=0.0
Laminate Layer 1 8.00 Resin Content 64.3% 3.2-6.0
Signal Layer 1 1.35 Width=6.0 Etchback=0.50
Laminate Layer 2 8.00 Resin Content 64.3% 3.2-6.0
Copper Plane Bottom 1.30 Opening w=0.0 offset=0.0
Layer Thick Er Loss Tangent
Copper Plane Top 1.30 3.20
Laminate Layer 1 8.00 4.20 0.00120
Signal Layer 1 1.35 3.60 0.00120
Laminate Layer 2 8.00 4.20 0.00120
Copper Plane Bottom 1.30 3.20
Rdc_trace_1= 91.41 milliohms/in 20C
DC resistance by pixel count:
Rdc_trace_1= 88.603 milliohm/in.
C = 3.314 pF/in L = 8.948 nH/in.
Er = 4.131 Loss_tan = 0.00120
Zo = 51.964 Ohms Delay = 172.202 ps/in.
Log file save name:
mdtlc_12071642483.txt
Log file save name:
________________________________
From: ryansatrom <ryan.satrom@xxxxxxxxxxx>
To: si-list@xxxxxxxxxxxxx
Sent: Thursday, August 16, 2012 10:47:23 AM
Subject: [SI-LIST] Stripline Propagation Velocity
Hello All-
I took some VNA measurements on PCB's manufactured with several different
materials.
Each PCB material had two 50 Ohm stripline traces on different layers: A
trace between two 4 mil cores, and another trace between two 8 mil cores.
I expected that the propagation velocity of two traces to be the same, but
measuring the propagation delays indicated that they were not (the PCB
launch and vias were calculated out.)
Of the six different PCB materials that I measured, five of them were
faster on the stripline trace between the 4 mil cores. The differences in
speeds were outside the range that could be attributed to measurement
error or manufacturing tolerances.
What can the differences in speeds be attributed to?
Thanks,
Ryan
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