IC Packaging and SiP Blogs

It is quite common to reuse memory stacks across designs. These memory stacks are created as modules (.mdd) and saved in a library, which can then be used in different package designs. You can place a memory stack module depending on the capacity of the design. This process saves a lot of time and resources. In this post, we will learn about a couple of important enhancements that have been made to the module creation flow in the HotFix 019 of 17.4-2019 release of Allegro® Package Designer Plus.

Die Stack Support for Modules

Before HotFix 019, the Die-stack Editor support for the module design was missing, thus reusing the memory stack module required a lot of rework. The following image shows the missing die-stack related information in module design.

Reusing this module(.mdd) in a package design places the dies on incorrect layers and makes the wire bonds disconnected from the pins.

The Die-stack Editor has now been enhanced in HotFix 019 and supports modules. The next image shows the updated Die-stack Editor in module design with correct die placement for the memory stack. The memory stack created as a module(.mdd) can now be reused in any package design.

Placing Modules in Other Designs

To place a module in a design, follow these steps:

1. Run the place manual command in the Command window.
2. In the Placement dialog, select Module Definition under the Placement List.
3. Choose modules present in the library to place in the design.

The module will have the correct die stack layer and wire bond connectivity after it is placed in the design. The next image shows the placed module and its respective die stack details in the Die-stack Editor.

Updating Memory Stack Module in a Design

Any change to the memory stack has to be done in the parent module. To update the module definition in the package design, follow these steps:

1. Choose Place ─ Update Symbols.
2. In the Update Modules and Symbols dialog, select the modules you want to update in the design.
3. Click Refresh.

The command updates all the selected modules with their new definitions in the design.

The following image will give you an idea of how the newly-added bond wires on power and ground pins look after refreshing the module.

Replacing Memory-Stack Module in a Design

Another way to update a module is to use the Replace modules command. When in the Placement Edit application mode, this command is available as a pop-up option. To replace a module, follow these steps:

1. Select the module in the design canvas.
2. Right-click and choose Replace modules.
3. Select the updated module from the sub-menu list.

The module is replaced with the selected module.

That is how you can save multiple versions of a module with different names.

You will agree that updating the module is now easier than before. So, the next time you plan to reuse memory stack modules, you can leverage the new capabilities available with Allegro Package Designer Plus.

Do SUBSCRIBE to be updated about upcoming blogs. If you have any topic you want us to cover or any feedback, you can write to us at pcbbloggers@cadence.com.