Remove Die Stack Layers from NC Drill Outputs using Cadence 16.6 SiP and APD IC Packaging Tools

 As we continue with our series on improvements to the manufacturing and documentation outputs in the Cadence 16.6 IC Packaging layout tools, our focus this week is on NC Drill outputs.

For as long as NC Drill data has been a part of the IC Packaging tools, and the cross-sections in package designs have had die stack (die in APD) layers, NC outputs have included these layers in their outputs. This means that the first layer of the actual package substrate would not be layer 1 in the NC drill data. It would be layer 2, 3, or the next number after counting all the die stack type layers. Many designers would rather not include the die stack layers; instead, they would prefer that the first substrate layer be layer 1 regardless of the number of die stack layers present.

With 16.6, these designers are in luck! You now have the option to control whether or not die stack layers are counted in NC drill outputs. To learn how to control this setting and eliminate any manual editing you may be doing in your current flows around NC drill data (not to mention the other commands that have been updated in this same manner), read on!

Ignoring Die Stack Layers in NC Drill Outputs

Because many designers are accustomed to how the tool works today (and some of you may even have processes and scripts in place to massage the exported NC Drill data), you will need to enable this change to your NC Drill output in your environment. This is easily done by setting the environment variable from your Setup -> User Preferences command as shown in the image below:

Once this variable is set, you must restart your tool session in order for it to take effect. For consistency across all designers in your company, it is recommended that this be set for all users either in manually or at the CDS_SITE environment configuration level. Do this to ensure that you get the same results regardless of who generates your NC Drill data.

Shown below is a sample cross-section from SiP Layout and the differences you'll see between the old NC Drill behavior and the new, once the variable has been enabled:

As you can see, drills between TOP_COND and M1, previously shown as between layers 5 and 6, now show as being between layers 1 and 2. This is a much more natural numbering convention and the output indices won't change if you add more die stack layers (or named dielectric layers for spacer symbols) above TOP_COND or below BOT_COND.

.. And It's Not Just NC Drill

NC Drill outputs, while perhaps the most consistent area of trouble for designers, isn't the only place where designers only want to factor the actual package substrate layers into their layer counts.

With that in mind, if you enable this new feature, not only will NC Drill outputs change, but so will the Cross Section Charts you generate with the Manufacture -> Cross Section Chart command. Via span labels, on the other hand, (enabled from the Setup -> Design Parameters command) always reference the package substrate layers only, as vias are not permitted outside the substrate. 

Upgrade to 16.6 today to streamline the output of your NC Drill data and Cross Section Charts. If you have another command which you think should follow this environment variable's control, or if you have any comments or suggestions for improving your productivity in general, we'd love to hear from you!

Jeff Gallagher