Have you ever integrated a mechanical design with an electrical design? Most of the PCB designers face this difficulty in transferring data between Electrical Computer-Aided Design (ECAD) and Mechanical Computer-aided Design (MCAD) worlds. This can cause frustrations for designers and also significantly increase the respins required to design a PCB. ECAD-MCAD Library Creator allows you to easily integrate ECAD and MCAD designs by leveraging a 3D STEP Model provided by leading vendors for use in ECAD footprint generation.

In my previous blog posts, we already discussed creating a footprint from a package and using a template stored in the ECAD-MCAD Library Creator repository. In this blog post, let us discuss how a vendor-provided STEP Model can be used to create a footprint using Allegro Library Creator.

What is a STEP Model?

STEP or Standard for the Exchange of Product model data (ISO 10303) is an international standard widely used for exchanging three-dimensional geometric models between mechanical CAD/CAM, CAE, and PCB tools.  While many leading PCB tools provide the ability to import 3D STEP models for use in 3D visualization, Allegro ECAD-MCAD Library Creator is the only tool capable of directly leveraging 3D STEP models for creating detailed and accurate PCB footprints.

So, let’s discuss how to create a footprint from a 3D STEP Model provided by a vendor.

1. Importing the STEP Model

Importing a STEP Model provided by a vendor is a fairly easy process in Library Creator. Just choose File – Import – Step, select the .stp file, and click Open to import a 3D STEP Model. That’s it. The STEP Model is imported and displayed in the 3D view.

You may also want to edit the seating pane to its correct position.

2. Specifying Contact Areas

Library Creator provides multiple methods to specify contact areas. In many cases, you can easily generate contact areas by just right-clicking the unassigned Solid Model entry and choosing a feature from the Contact Features menu.

This creates groups under Features - Unassigned in the Explorer pane. Library Creator is intelligent enough to create groups of all the objects that are of the same size. For signal pins, Library Creator uses the terminology Terminals. Drag and move these groups to the Features – Terminals. This completes the task of specifying contact areas.

3. Assigning Terminal Types

This is again an easy task in Library Creator. To assign terminal types, right-click the group under Features – Terminals and chose a lead form from the Set Lead Form menu.

4. Assigning Model Height

When creating a footprint from a STEP Model, it is important to assign the height parameter for the model. You can do this by right-clicking the model name in the Explorer pane and choosing Parameters – Edit. Now select the Height check box and click Compute. Library Creator automatically computes and displays the height.

5. Assigning Pin Numbers

Library Creator provides multiple options to assign numbers to pins. You can use the sequential or array numbering pattern to assign pin numbers. Assign pins by selecting the pins and then clicking the appropriate numbering tool. This will automatically assign pin numbers based on the numbering tool you have selected.

6. Applying Rules to Footprint

Now it is time to make your footprint as per the industry standards. Applying rules to your package is an important step as this makes your footprint compliant with the industry standards, such as IPC-7531. In this step, you just click the Apply menu and then select a rule.

7. Saving the Footprint

It is important that you save the changes to the Library Creator repository. Just choose File – Upload – Save New Version to upload the footprint to the repository.

Conclusion

And, that completes creating a footprint from a vendor-provided STEP Model. If you want to try out the steps, you can do that with a sample design using the Rapid Adoption Kit (RAK) on creating a footprint using a STEP Model in Library Creator.

Note: The above link can only be accessed by Cadence customers who have a valid login ID for https://support.cadence.com.