PCB Design Best Practices: Design Automation

Design automation stands out as a subject close to my heart. When delving into the realm of design automation, three key concepts immediately come to mind: optimization, efficiency, and speed. 

I still remember the first time I used automation to route signal traces, about 20 years ago. It unfolded amid the usual chaos of a project deadline, a familiar scenario in the project design cycle: "We need it completed today! Oh, and by the way, there are additional design changes for you to incorporate, but the deadline remains today!" 

For the first time in my career, I used the autorouting feature in my tool. Talk about an uneasy feeling, like a stomach cramp. It was gut-wrenching to let go of my manual approach for designing PCBs, especially knowing I was under a very stressful and tight project time constraint. However, much to my surprise and amazement, the autorouting implementation proved successful. Not only did I meet the deadline, but I also completed the task earlier than anticipated, leaving the electrical engineer I collaborated with, as well as the entire project team, astonished. To add to the triumph, I presented several alternative versions of the design for the engineer to choose from. Success! What a feeling! One of the highlights of my career, for sure. I have never looked back. Since then, I have wholeheartedly embraced the power of CAD tools, emphasizing the importance of leveraging their full capabilities.   

In fact, I am such a fan of automation that tomorrow, Nov. 14, I’m hosting a special LinkedIn livestream conversation on the topic. I hope you’ll join me — you can RSVP here. My good friend Ray Macias will be joining us. He’s an expert at using automation for PCB routing. I also hosted him earlier this year on the Printed Circuit Podcast to discuss design automation. You can tune in here to get a preview of tomorrow’s discussion.  

What is PCB design automation?  

There are many functions or processes within PCB design that can be automated, including: 

• Placement: 3D component planning and placement provides correct-by-construction placement while considering electro-mechanical constraints.   
• Clusters: Also referred to as Groupings or Unions, Clusters is when specific components within a respective circuit or set of circuits are assigned to a group consisting of many components. Once a group of components are assigned to a cluster, that cluster can be treated as if they are an individual component during placement. These clusters are initially created and defined within the Constraint Editor (CES). Then, when an electrical engineer is selecting components during circuit creation of the schematic, he/she can assign each component to a specific cluster, respectively. Then that specific cluster can be given a unique name that is relevant to the circuitry at hand for a better circuitry identification during the PCB Design process.   
• Routing: powerful automated routing technology enables extraordinary efficiency during PCB layout. Unravel complicated net paths and pin escapes to minimize net lengths and quickly and easily identify the best routing strategies. Designers can manually (interactively) route traces or use the automation in auto-routing in a controlled manner, or they can utilize a combination of the two routing processes to achieve their specific routing requirements for overall success.   
• Sketch routing: sketch routing provides a set of highly integrated automated routing functionalities featuring intuitive user control, high quality, and exceptional performance.   
• Manufacturing output: Whether the outputs contain one specific set of data or several files such as ODB++, IPC-2581, Gerber data, an IPC-356 Netlist, GENCAD data, ICT files, etc., the generation of these file can be automated to be consistent from design to design and or tailored to your internal company standards and or your PCB fabricator and assembly manufacturer.   

How it works: design automation – placement   

When placing components in a layout, one way to speed up the process, besides the utilization of reuse circuitry (reuse blocks or reuse modules), is by using component groups. While reuse blocks assist in adding pre-placed and pre-routed circuits, component groups help keep parts together that may not be part of a reuse block within the library, that should be placed near or within a specific proximity to each other on the board. 

Component groups still show the user netline connectivity between themselves and other components, which can help in determining the best placement or location for groups of components. They also are sized based on the size of the components within them, to help determine the board real estate that each group may take up or occupy. 

How it works: design automation – routing   

When it comes to routing, automation is the key to increasing productivity (optimization and efficiency). While Xpedition has a powerful autorouter, many times it makes sense to use a more manual interactive approach which allows more hands-on control of each, and every signal trace being routed. A what-if approach utilizing the autorouter is a great option to take advantage for routing automation, which increases the potential for routing optimization and efficiency. Lastly, a combination of both autoroute and interactive routing will provide the best and highest potential in achieving success, in regard to routing optimization and efficiency. 

Using sketch planner allows users to start to plan where routes will go, and it can even be used before all the components are placed. A good example of this would be when the designer is using sketch planner to create blind sketch plans for single pin routes going to a yet-to-be-placed connector. With the plans created, the pins can be broken out, and routes started. Once the connector is added to the board, using sketch route makes quick work the remainder of the connection. 

How it works: design automation – manufacturing output   

When the PCB design is 100% completed (all components placed and signals routed), has passed all signal analysis/verification to include manufacturing and producibility analysis/verification, and has passed final reviews, the time comes to generate all the required outputs for board fabrication and board assembly manufacturing. Generating all the required manufacturing outputs is another area where you can use automation to save time and remove redundant steps. 

Whether the outputs contain one specific set of data or several files such as ODB++, IPC-2581, Gerber data, an IPC-356 Netlist, GENCAD data, ICT files, etc., the generation of these file can be automated to be consistent from design to design and or tailored to your internal company standards and or your PCB fabricator and assembly manufacturer. The legacy methodology of manually doing each step or task individually to generate each required output file is time consuming, potentially inconsistent each time in generating output files, and prone to potential output files being missed or not generated during the output generation stage of the PCB design process for all the required output files, even if an external checklist is manually being used. Content correctness, quality and consistency is key in setting up your board fabricator and board manufacture for success in producing your required printed circuit assembly. 

Learn more about PCB design automation  

If you want to learn more, check out this eBook I wrote: PCB Design Automation 101. It is free to download and will take you through the ideas we discussed here in more detail. I also suggest you read this blog post from Ray, “PCB Routing: art + automation.” He gives some great tips! And finally, I welcome your questions on this topic at tomorrow’s LinkedIn livestream. Looking forward to connecting with you!