A smooth workflow is critical to the success of any design project.
Important productivity enhancers to look for in PCB layout tools.
Other factors to consider beyond the capabilities of the tools.
Without the right tools, the job may not get done.
If you’re like me, you’ve probably been in a situation where you didn’t have the right tools to complete a home repair correctly. Whether it is trying to repair a broken toy, tighten up a door hinge, or replace a faulty wall switch, not having the right tools can cost you your time and money, as well as a good mood. Broken drill bits, rounded Allen wrenches, dull blades, and a pleasant evening at home are just a few of the casualties that come to mind.
Whether you are just starting out designing electronics or you are looking at upgrading your current processes and systems, it is just as important to use the right design tools as well. There are many different PCB design CAD systems to choose from, and they all have different capabilities and features. The key to your success will be to evaluate the tools you are considering against the needs of your design technology, as well as your workflow. Here are a few ideas about the features in PCB layout tools to look for.
A Smooth Workflow
One of the most important aspects of choosing which PCB layout tools to work with is how the different tools within the system work together for a smooth workflow. Although it can be tempting to look only at specific features, such as auto-routing technologies, you will ultimately be working with the entire system to design circuit boards. Therefore, the CAD system you choose should be able to process the design through these four major areas with the different tools and features that they offer:
Schematic capture: Not only will this tool allow you to capture the logic of the design by placing components and routing nets between pins, but it should also capture your rules and design intent to pass it on to the layout tools.
Circuit simulation: Once the schematic has been captured, it should be simulated with SPICE (Simulation Program with Integrated Circuit Emphasis) tools to find problems and optimize the circuitry before going to layout.
PCB layout: These tools transform the net and component information of the schematic into physical representations that can be arranged, or laid out, to design the actual circuit board.
Signal and power integrity analysis: Once the arrangement of the physical components and their interconnections has been completed in layout, the integrity tools are used to verify the maximum electrical performance of the circuitry.
Another area that should be part of your evaluation is the library system that accompanies the CAD tools that you are choosing. The schematic, circuit simulation, and PCB layout tools will all use different types of library models or parts to do their work. It is imperative for a successful workflow that these library parts can easily be created or retrieved from external sources. Without a good library in place, circuit board design can be slowed down by the need to constantly rebuild the same parts, or bad parts can undermine the successful manufacturing of the board.
With a good CAD system identified for its tools and workflow, let’s look next at some of the different features in PCB layout you should focus on.
A PCB design rules and constraint management system.
Productivity Enhancements in PCB Layout Tools
As you know, the purpose of the PCB layout tools is to place physical representations of components on the board design and connect the pins together with metal traces. Every PCB layout system out there will do this in one way or the other, so the important thing is to select tools based on the features that will help you to be more productive in your work. Let’s look first at managing design rules and constraints in the layout tools.
To lay out a printed circuit board that will perform electrically and be manufacturable without errors, the designer must obey design for manufacturability (DFM) rules and electrical constraints. How these rules and constraints are managed differ between CAD systems, but the most efficient tools offer a spreadsheet-style entry utility to manage all of the data in one interface. These types of management systems allow for easy access to the rules and are often available in the schematic tools as well as the layout.
Another area of productivity in layout that can be enhanced is in the trace routing itself. The more advanced the PCB layout CAD system is, the more routing features it will have. Look for the following trace routing features when considering a new CAD system, as they can carve a lot of time out of your routing efforts:
Automated systems to help with escape routing out of large pin-count parts such as BGAs.
Free-hand routing tools to allow you to easily “scribble” your routing in place while the system puts in the actual vertices and trace segments.
Auto-interactive routing that allows the designer to map out the direction of large groups of nets for the best electrical performance and signal integrity.
On-the-fly routing that allows a designer to easily select and automatically route non-critical nets saving a lot of manual routing time.
Full batch mode auto-routing that can take an entire PCB design and automatically route it following the rules and constraints.
In addition to the routing features, it is also important that the system you use has mechanical co-design capabilities as well. These allow you to import mechanical features such as shields, cables, or system enclosures into your board for clearance checks to your component placement. Usually, there is a 3D viewing method that allows the designer to see exactly what the complete system design will look like as well.
There are many other features in the tools that you should look at as well, but let’s talk next about some other non-tool specific details that are also just as important.
Using a CAD tool with 3D capabilities, like OrCAD PCB Designer, can enhance your routing strategies.
Continual Improvements and Upgrades
Knowing who you are dealing with when it comes to choosing a CAD system is just as important as how the tools work. Here are some things that you should keep in mind:
What is their corporate culture like? Do they support their customers in achieving the next level in their designs?
Do they offer a wide range of technical support and training? Make sure to look for what kind of company documentation is available online, as well as how-to videos and regular training programs.
Do they regularly come out with tool enhancements as well as new features and new products?
One example of a PCB design system that has the features and capabilities that we’ve talked about here is from Cadence. OrCAD PCB Designer offers you a complete system solution from schematic to layout, along with circuit simulation and integrity analysis tools as well. You will find some incredible productivity enhancers within OrCAD, along with some of the most advanced PCB layout features on the market today. With OrCAD, you will also have access to a wealth of support and training from Cadence, the leader in EDA design today.
If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.
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