
SEARAY CONNECTOR ROUTING GUIDE
REVISION: ECR/ECN INFORMATION: SHEET No.
EC No:
UCP2010-1365
A DATE:
2009/12/01
TITLE:
SEARAY BOARD TO BOARD SYSTEM
CONNECTOR ROUTING GUIDE 12 of 14
DOCUMENT NUMBER: CREATED / REVISED BY: CHECKED BY: APPROVED BY:
AS-45970-990 GREGORI SQUIRE / STANCZAK COMERCI
Layer allocation
To avoid stub effects it is recommended that high speed differential pairs be
routed on the bottom layers of the PCB board. Use of embedded micro-strip routing on
the top layer and strip-line traces with micro-vias on the upper layers can allow high
speed routing on the upper layers with minimum stub effects. Middle layers should be
used with caution when routing high speed lines. If middle layer must be used then back
drilling is highly recommended to optimize impedance and minimize crosstalk.
III. CROSSTALK TX AND RX ARRANGEMENT
Cross talk is strongly influenced by the rise time of the input signal. High-speed
signals can show significant increase in cross talk relative to lower speed signals in the
same channel. For this reason careful consideration of signal arrangement should be
made. It is recommended that Tx and Rx signals be grouped together in separate
blocks to minimize cross talk. In addition high-speed signals can be separated by power
return and low speed signaling to further increase crosstalk isolation. It is also
recommended that Tx and Rx signals be routed out on different layers to increase cross
talk isolation between traces
Table A: TX RX grouping separated by low speed (LS) signal columns
1 Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx Rx Rx
2 Tx Tx Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx
3 Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx Rx Rx
4 Tx Tx Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx
5 Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx Rx Rx
6 Tx Tx Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx
7 Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx Rx Rx
8 Tx Tx Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx
9 Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx Rx Rx
10 Tx Tx Tx Tx Tx Tx SE/P SE/P SE/P SE/P SE/P Rx Rx Rx Rx
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
A B C D E F G H J K L M N O P R S T U V W X Y Z AA AB AC AD AE AF
Single 2:1 Diff Pairs 1:1 Diff Pairs Fully Shielded
Low speed single ended / Power