The Add Connect with Offset command in Allegro PCB Editor 16.6 is designed to primarily address the requirement to route with non-standard angles to help minimize impedance discontinuities while routing across fiberglass substrates. Other routing applications may be applicable as a result of this implementation, including, but not limited to, package/connector breakout or routing associated with tester cards.
The Offset Routing command is integrated into the standard Add Connect command and is available in all Allegro product options.
Options
- Route offset mode: Checkbox for "Add Connect" to use the route offset angle
- Default setting = Off
- Route offset angle: A two-decimal fill-in field for entering the offset angle
- Default setting = 10.00 degrees
- Range = 4 to 18.5 degrees
- Line Lock: Must be set to Line = 45
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Function Keys
- TAB key: Use this system-defined key to switch between a soft bend (first angle increment) and a hard turn (second angle increment). Each time that you hit the tab key, it will flip to the other angle.
- funckey a ‘pop flip’: Consider creating a user-defined function assignment to help you toggle between conventional and offset routing. The letter ‘a’ is used as an example only.
Read on for more details …
In order to initially see the affects of the offset routing capabilities, you might consider making an adjustment to your datatip configuration to display the angle of the routes. At various times during the upcoming steps, you may want to hover over a segment and check the angle.
a. Setup – Datatip customization
b. Select "Segment"
c. Enable "Normalized angle"
In the command window, type - funckey a ‘pop flip’ (this step is not necessary if this function key is already in your local env file). Invoke "Add Connect" and begin routing one of the diff pairs associated with the bundle. Try to follow the path of the bundle as best as you can. Here’s an example in Allegro PCB Editor:
At the point where the bundle shifts upwards, enable "route offset", then enter the angle 11.3 degrees. This is a common angle we see in the industry:
Continue to follow the contour of the bundle, making a pick at each vertex point to toggle between +11.3 and -11.3 degrees:
As you approach the horizontal section of the bundle, click the ‘a’ key to unset "route offset" mode. Route the horizontal path, then take a 45 degree turn:
At the end of the 45 degree section, click the "a" key to resume offset routing, noting the soft angle shift of 11.3 degrees is not in alignment with the bundle. The angle is 56.3 degrees (45 + 11.3):
Press the TAB key to perform a "hard" angle shift. Angle is 90 – 11.3 = 78.7:
The transition from the 45 degree route to offset derivatives is outlined below:
Click the TAB key again, then the "a" key to resume conventional routing. This may seem unrealistic but switching from offset <> conventional is common:
Click the "a" key to resume soft offset routing and perform a few zig-zags. End the route just before the device pins:
Let’s route the remaining three diff pairs as a group. Begin by pre-routing the pairs as shown in the figure below:
Invoke "Add Connect", then window-select the three diff pairs. You should now be in group route mode. Extend the routes to the right, then use RMB – Contour – Cline to follow the path of the adjacent cline. The routes at this stage of the contour lock may offset slightly, as shown in the graphic below:
Now that you are in the contour lock mode, simply glide your cursor over the route you have locked onto. Note the minimal effort that was applied!
With contour routing, some level of adjustment is usually necessary near the transition of the initial contour lock. Feel free to use the Slide function to smoothen out the routes:
Please share your experiences using this new feature.
Jerry “GenPart” Grzenia