AN2013_7 PADS Layout/Stackup Planner Bidirectional Interface

© 2013 In-Circuit Design Pty Ltd | Australia Page 1

The Stackup Planner/PADS Layout bidirectional interface exports PADS Electrical Layers into

ICD Stackup Planner for the calculation of impedance and trace current. The stackup can then be

modified in Stackup Planner—to obtain the desired impedances—and imported back into PADS

Layout.

Licensing: A 14-day license is included with download. Contact Sales@icd.com.au for permanent license.

Importing a Stackup from PADS Layout into ICD Stackup Planner: Whether you’re starting with a legacy stackup in PADS, or a default stackup that needs

refinement and impedance planning—based on actual dielectric materials, thicknesses, and

dielectric constants—ICD Stackup Planner is an ideal companion product for PADS users.

To bring a substrate design into Stackup Planner from PADS, perform the following steps:

1. Open the PCB database in PADS Layout, and select File > Export > Save.

2. The ASCII Output dialog opens, as shown above.

3. Click the Select All button, and OK. An .ASC file is created, exporting everything in the

PADS database, including both Electrical Layers and General Layers.

4. Open ICD Stackup Planner.

5. To import the Electrical Layers from the PADS ASCII file into ICD Stackup Planner, select

Import > EDA Translators > PADS, and navigate to the PADS ASC file, as shown on the

following page.

6. A new stackup tab will appear in Stackup Planner, using the following decision rules for

dielectric layer creation:

• PADS dielectric layers default to Substrate. Substrate layers in PADS will result in

Core layers in Stackup Planner.

• If a dielectric layer is identified as a Prepreg layer in PADS, this will be assigned as a

Prepreg layer in Stackup Planner.

• If a dielectric layer is identified as a Solder Mask layer in PADS, this will be assigned

as a Solder Mask layer in Stackup Planner.

AN2013_7 PADS Layout/Stackup Planner Bidirectional Interface

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7. Note that PADS defaults to all dielectric layers as “Substrate,” with dielectric constants of

4.3 and dielectric thicknesses of 10 mils, as shown above.

8. The new stackup will show the following for metal-layer creation:

• If a metal layer is identified as a Routing layer in PADS, this will result in a signal

layer in Stackup Planner. Signal layers in this version of the PADS interface assign trace widths to 4 mils, with differential clearances of 8 mils in Stackup Planner.

• If a metal layer is identified as a CAM Plane in PADS, this will be a Plane layer in

Stackup Planner.

AN2013_7 PADS Layout/Stackup Planner Bidirectional Interface

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• If a metal layer is identified as a Split/Mixed layer in PADS, this will result as a Plane

layer in Stackup Planner. (More options on Split/Mixed layers will be provided in a

future release. In the meantime, right click on a layer, and select Swap Plane/Signal

to toggle back and forth for impedance calculations.)

9. Adjust trace widths, spacing, layer thicknesses, copper thicknesses, and dielectric

materials in Stackup Planner to achieve the desired single ended and differential

impedances for each layer. (Note the changes in the view below.)

Note: If layer sequencing needs to be changed, it should be performed in PADS in order to

preserve the integrity of your design database. (I.e., do not change the layer sequence in Stackup

Planner.)

Exporting a Stackup from ICD Stackup Planner to PADS Layout: 1. In Stackup Planner, select the specific tab to be exported.

2. Select Export > EDA Translators > PADS.

3. Navigate to the PADS Filename.ASC file that was exported in Step 3, above. Select the

file, and click the Save button. A file called Filename-SP_edits.asc will be created, with

edits to the Electrical Layer information from the original PADS database

4. Go back to PADS Layout, selecting File > New, to avoid overwriting the original PADS

database.

5. Select File > Import, and navigate to Filename-SP_edits.asc. Select OK.

6. Select Setup > Layer Definition in PADS.

AN2013_7 PADS Layout/Stackup Planner Bidirectional Interface

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7. Select the Thickness button to open the Layer Thickness dialog.

Verifying Stackup Changes in PADS:

1. Press the Windows button on your keyboard (next to the ALT button), and the left

arrow simultaneously.

2. Press ALT and Tab to select Stackup Planner; then press the Windows button again, and

the right arrow simultaneously. PADS’ Layer Thickness dialog should be visible on the

left half of the screen, and Stackup Planner on the right half, as shown below.

3. Verify that the layer thicknesses, copper thicknesses, and dielectric constants are the

same. (Note; Stackup Planner will not change layer names in PADS.)

Note: An upcoming revision to the PADS-to-Stackup Planner import will include default trace

widths and clearances from PADS. The export to PADS will include net-class rules that can be

conditionally assigned in PADS.