IC Packagers: Optimizing Connectivity Between Die Escape Routing and BGA Balls

Package designers need to add escape routes to a die to facilitate further package routing: these routes provide essential pathways for signals to exit the die and reach other parts of the package or PCB. Without well-planned escape routing, signal traces can become congested or blocked, especially in high-density designs, leading to increased complexity, longer trace lengths, and potential signal integrity issues. Escape routes help optimize the layout by ensuring that each I/O pad has a clear and efficient path to its destination, improving electrical performance and manufacturability.

Integrity System Planner enables system and package engineers to aggregate data from IC, package, and PCB design teams, allowing them to perform key system planning tasks such as component placement and the definition and optimization of interconnectivity between components. Its connection optimization feature relies on selecting a subset of a component’s pins, with one side fixed and the other side free, allowing net assignments to be updated dynamically. Escape routes, on the other hand, are part of the physical implementation within the package design tool and are typically not recognized as pins when imported into Integrity System Planner.
However, it is important to consider the fanout pattern from the die escape routing during the optimization process. Once escape routes are created, optimizing connectivity from die pins to BGA balls may no longer yield optimal results, potentially leading to tangled or inefficient connections.
The post aims at guiding you through the process of creating a new component based on an existing die escape routing in Allegro X Advanced Package Designer. This new component will have pins located at the end of the breakout routing and can be imported into Integrity System Planner for further connection optimization.

Overview of Component Creation and Connection Optimization 

The following figure shows the overview of the new component creation in Allegro X Advanced Package Designer and its transfer to Integrity System Planner where the connection optimization can be performed.

In the following sections, an example is used to perform the following four steps to demonstrate the optimization process:

1. Generate die escape routing in Allegro X Advanced Package Designer

2. Create a new component in Allegro X Advanced Package Designer

3. Import the Allegro X Advanced Package Designer database to Integrity System Planner

4. Optimize the connectivity between the escape routing and the BGA balls in Integrity System Planner

Step 1: Generating Die Escape Routing in Allegro X Advanced Package Designer

You can generate die escape routes using Route – Flip Chip Die Escape Generator.

Although the connections are optimized prior to die escape generation, rastnets are observed crossing on the northeast side of the breakout routing, indicating potential inefficiencies in the layout.

Step 2: Creating a New Component in Allegro X Advanced Package Designer

Load the SKILL context available in the Application Note database to be able to use new command, brk comp create. Enter the command to start creating the component.

Upon running the command, you are prompted to select two points to draw a rectangle around the end of the escape routes and to enter a reference designator name for the new component.

The component is then created with pins representing the endpoints of the escape routes, making it ready for import into Integrity System Planner for further connection optimization.

Step 3: Importing the Allegro X Advanced Package Designer Database in Integrity System Planner

Thanks to the interoperability of our tools, you can import the Allegro X Advanced Package Designer database into Integrity System Planner in the blink of an eye using Tools – Merge Updated Allegro.

The newly created BRK component, along with its associated connectivity, is seamlessly imported into Integrity System Planner, ready for further optimization.

Step 4: Optimizing the Connectivity Between the Escape Routing and the BGA Balls

In Integrity System Planner, you can optimize connectivity between two sets of pins: one set is fixed, meaning no changes are applied, while the other set remains flexible and can be updated.

On clicking Optimize, the connections are efficiently refined between the endpoints of the escape routes—represented by the BRK component’s pins—and the BGA balls.

Over to You

Do you want to try out this method? Delve deeper into the details of each step? Well, you can try out all the steps right away using the sample design available with the Optimizing from die escape routing to package balls in Integrity System Planner Application Note at Cadence ASK.

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You might also be interested in the free online Allegro X Advanced Package Designer Training and in the training videos available in the Training Byte Channel.

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