IC Packagers: Creating and Using Non-Rounded Via Stacks in Package Designs

The demand for smaller electronics devices can be achieved by high-density layers in multi-layer build-up substrates or multi-layered printed circuit boards (PCB). Vias are essential in the design and manufacturing process of multi-layered packages or boards. You use a via or a plated-through hole to route a trace from one layer to another. Although you can use through-hole or blind vias, these vias use too much space making routing difficult for complex and dense electronic devices. The solution is a stacked via, which has two or more layered vias on each other.

You can easily create stacked vias in your dense and complex designs using Allegro X Advanced Package Designer. In this blog post, we will discuss how you can use non-round stacked vias in a packaged design.

Create a Database

You start the process of creating a non-rounded stacked via by creating a database. Launch Allegro X Advanced Package Designer, create a new drawing using File – New, and save it.

Set-Up the Cross-Section

In this step, import the layer stack-up technology file and the parameter file using the Techfile and Parameter option in the File – Import menu. Choose Setup – Cross-section to open Cross-section Editor and view the layered cross-sections.

Set Drawing Property

The next step is to set the drawing properties. Just choose Edit – Properties and set the Find By Name field to Drawing in the Find filter. In the Edit Property dialog, set the Pad_Shape_Touch_Connections property to True and click OK.

At this point, you must also save the design by choosing File – Save.

Create a Shape Symbol

A new shape can be created easily in Allegro X Advanced Package Designer. To do this, you need to choose File – New, specify the name of the drawing, select Shape Symbol, and click OK.

Zoom in to the center of the display. Choose Add – Frectangle to draw a filled rectangle shape on the display to set the TOP and BOTTOM spacing coordinates. Save the symbol. A new .dra file is created at the location mentioned in the Project Directory field.

Modify Padstack

The main step when creating a non-rounded stack via is editing the padstack which is an easy task. Open the .sip file and choose Tools – Padstack – Modify Design Padstack. Select the shape from the Options tab and click Edit. This opens the Padstack Editor. Choose BBVia in the Start tab and save the padstack with a different name.

Under the Design Layers tab, change the values of layers in the Regular Pad column as displayed in the following image and save the padstack.

Placing Vias

The final step in the process of using a non-rounded stacked via is to place and rotate them on the package layers.

Conclusion

And, you are done! We have covered almost all the tasks involved in creating and using non-rounded stacked vias in Allegro X Advanced Package Designer in this blog. If you want to try these steps in detail, click here for the application note that describes these steps in detail.

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

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