16
Design and test of a prototype of a flex cable for high speed transmission Jan Buytaert (CERN), Daniel Esperante, Pablo Vázquez, Jevgenij Visniakov (USC)
Design and test of a prototype of aflex cable for high speed transmission
Jan Buytaert (CERN), Daniel Esperante, Pablo Vázquez, Jevgenij Visniakov (USC)
VELO Upgrade 24.6.2011 2
Design of the cable
What we have done
VELO Upgrade 24.6.2011 3
Measure the S-parameters of decoupled lines with a VNA HP8719D (13.5 GHz) in Santiago
Help with manpower to measure in other labs
What we can do
VELO Upgrade 24.6.2011 4
To prove that is feasible to build a high speed flex cable in CERN labs as no companies were found to produce longer than 55 cm (> 65 cm
needed) Characterize the transmission lines (31 in total) Test transmission through a fine pitch connector
Molex 5024304410
Cable design goals
VELO Upgrade 24.6.2011
Area 1: effect of a miniature fine pitch connector This area is cut-off in two pieces
Area 2: parameters of decoupled strip-lines Area 3: parameters of edge coupled differential striplines Area 4: effect of vias on gnd traces Area 5: length dependance: 0, 56, 75, 100 cm
Cable divided in areas for different studies
5
Area 2 (6 lines)
Area 1 (6 lines)
Area 5 (4 lines)
Area 4 (5 lines)
SMAconnectors
on both ends
Area 1 (6 lines)
570 mm (pyralux width – handling margin)
270
mm
Area 3 (10 lines)
VELO Upgrade 24.6.2011 6
Edge coupled differential striplines separated with gnd traces Made out of 2 foils of pyralux AP- PLUS AP7229R
Dielectric Constant = 3.4 Dissipation Factor (Loss tangent) = 0.002
Z is calculated with Rogers MWI-2010 tool which does not include Gnd traces overstimation (~ 5-10% ?)
Cable profile
Wd1 Wd2DDg1 Dg2
500 um
S+ S- GndGnd
18 um
GG
TOP
SIGNAL
BOTTOM
7
Two groups of 3 lines, one group per side of the connector (L1, L2, L3) = (L4, L5, L6)
L1, L2: S+ and S- match the pitch of the connector (L1 = L10 in Area3) crosstalk and impedance insertion loss of connector
L3: S+ and S- twice the pitch of the connector (L3 = L3 in Area 3)
Area 1: miniature fine pitch (400 um) connector
VELO Upgrade 24.6.2011
Coupled striplineL1 L2 L3 L4 L5 L6
Wd1 250 250 280 250 250 280Wd2 250 250 280 250 250 280
D 150 150 500 150 150 500Dg1 250 275 500 250 275 500Dg2 250 275 500 250 275 500
G 500 500 500 500 500 500Zdiff 94,6 94,6 102,7 94,6 94,6 102,7
Total W 2150 2200 3060 2150 2200 3060
8
(L1,L2), (L3,L4) and (L5,L6) are 3 pairs for differential transmission Impedance, crosstalk, bit error rate (BER) decoupled (area 2) versus coupled (area 3) transmission lines
(L3,L4) and (L5,L6): parameter ‘Wd’
Area 2: decoupled striplines
VELO Upgrade 24.6.2011
Decoupled stripline
L1 L2 L3 L4 L5 L6 Wd1 280 280 280 280 310 310Wd2 0 0 0 0 0 0
D 0 0 0 0 0 0Dg1 280 280 280 280 310 310Dg2 280 280 280 280 310 310
G 500 500 500 500 500 500Z 48,2 48,2 48,2 48,2 45,6 45,6
Total W 1840 1840 1840 1840 1930 1930
9
L1-L3: distance signal to signal ‘D’
L3-L5: distance signal to gnd ‘Dg’
L3, L6: width of signal ‘Wd’ (D=500)
Area 3: coupled differential striplines
VELO Upgrade 24.6.2011
Coupled stripline
L1 L2=L8 L3 L4 L5 L6 L7 L8=L2 L9 L10
Wd1 280 280 280 280 280 310 250 280 310 250
Wd2 280 280 280 280 280 310 250 280 310 250
D 750 250 500 500 500 500 250 250 250 150
Dg1 500 500 500 400 300 500 500 500 500 250
Dg2 500 500 500 400 300 500 500 500 500 250
G 500 500 500 500 500 500 500 500 500 500
Zdiff 104 96,7 102,7 102,7 102,7 97 102,5 96,7 91,6 94,6
Total W 3310 2810 3060 2860 2660 3120 2750 2810 2870 2400
L7-L9: width of signal ‘Wd’ (D=250)
L10: D=400 um
10
L1-L5 = L1-L5 of Area 3 (whitout vias on gnd traces) No vias gnd traces width ‘G’ = 300 um
Area 4: striplines without vias on gnd traces
VELO Upgrade 24.6.2011
Coupled stripline
L1 L2=L8 L3 L4 L5
Wd1 280 280 280 280 280
Wd2 280 280 280 280 280
D 750 250 500 500 500
Dg1 500 500 500 400 300
Dg2 500 500 500 400 300
G 300 300 300 300 300
Zdiff 104 96,7 102,7 102,7 102,7
Total W 3310 2810 3060 2860 2660
VELO Upgrade 24.6.2011 11
TOP ground layer
VELO Upgrade 24.6.2011 12
SIGNAL layer
Lines are routed turning left – right to equalize all trace lengths
Grid to avoid delamination
VELO Upgrade 24.6.2011 13
DRILL layer
VELO Upgrade 24.6.2011 14
BOTTOM ground layerOpenings on top/bottom layers to allow quality evaluation:
gluing, etching… of traces (and cutting-off)
VELO Upgrade 24.6.2011 15
Surface mount SMA and find pitch connectors mounted directly on signal layer to avoid vias on signal traces
4 vias close to SMA connector and 1 via every 10 mm on gnd traces to improve ground connection
Detail: end of transmission lines
VELO Upgrade 24.6.2011 16
Detail: fine pitch molex connector
