Parameters for PCB Layout
Why are all of these different layout setup parameters necessary?
What are the most beneficial parameters to change for productivity?
How to work with the setup parameters in your PCB design CAD system.
The setup icon used for setting up or altering the parameters for PCB layout.
Most everything that we use today has some sort of set up that needs to be done before it can be operated. That new computer or smartphone that we’ve just purchased is certainly no exception, as are power tools, appliances, and other household items. And don’t even get me started on kit furniture. Those evil things have way too much that has to be set up, which doesn’t really matter anyway because what comes in the box doesn’t ever seem to match the attached instructions. Another item that has a lot of parameters to set up is the CAD tools that we use for laying out printed circuit boards.
When you aren’t used to a new set of PCB design tools, the amount of setup that goes into the parameters can seem to be overwhelming. There are, however, very good reasons for all of these parameters, and with the right touch on the controls, your layout tools can be made to conform to your method and style of designing. Here are some of the problems that these parameters for PCB layout are intended to solve and how by working with them, you can fine-tune your design environment for maximum productivity.
Why Do We Need All of These Parameters for PCB Layout in the Design Tools?
Since PCB design tools were first introduced, layout engineers have been asking for more and more features and functionality. Design tools from 40 years ago would allow you to move parts around and draw traces, but there were few capabilities beyond that. Individual component footprint changes were difficult to manipulate, area fill (copper pour) features were primitive at best, and there were many other restrictions on how you worked due to the limitations of the tools. As time went on, though, those limitations were eliminated with advances made in both hardware and software. But, those advancements introduced a new set of problems that had to be dealt with; all of these new features required more and more setup time to run properly.
As layer counts increased, it became more difficult to visually identify each design element on the screen, and as new routing and area-fill functionalities were added, the existing grid and rule structures weren’t able to control them. These are just a few of the important problems that needed to be resolved due to increasing the design capabilities of the tools. If you’ve ever worked on a 16 layer board using a design system from 35 years ago that only offered a monochromatic display, you would know what I mean. Without the ability to set up different colors, it was nearly impossible to use.
To give users more flexibility in using the newly enhanced capabilities of PCB design CAD systems, EDA vendors began to include more and more parameters that needed to be set up for layout. When using a new set of design tools these parameter setups can be a little overwhelming but there are very good reasons for all of them, even if they all don’t get used by each user:
Units of measurement, tolerances, fonts, text sizes, and other standards that vary from company to company.
Some people will see colors and patterns differently than others and have to be able to change the display as needed.
Display schemes that may look good for some tasks, such as library development, may be distracting or difficult to see through during layout.
Parameters such as grid settings that benefit one user may be difficult for others to use in the same tasks.
The display scheme used by an individual user may be very difficult for a group to work with during a design review.
There are, of course, many other reasons why the parameters of a CAD system would need to be changed--these are just a few examples. Next, let’s take a look at what some of the parameters are that PCB designers would most like to be able to change.
PCB designers need more flexibility in being able to assign different colors to specific net elements.
The CAD Parameters That Would Be the Most Beneficial to Change
Getting a PCB design system set up for the most productive work environment means being able to change the parameters of the tools as needed. Here are some of the parameters that designers need to be able to work with the most:
How the Design Is Displayed
Toolbars and commands: Being able to reposition toolbars as well as the commands within them is one of the top items on the list for making design tools more usable. Although this doesn’t affect the design itself, it does help improve the user’s productivity when they can organize favorite commands and workflows.
Colors: Being able to change colors has been a user-configurable parameter for a long time now, but users are always seeking more control over the depth of these choices. Designers not only want to set up a color choice for a layer, but also by net, groups, or design objects as well. This can be very useful when working with multiple power and ground nets that have to be separated.
Patterns and fills: Along with colors, this is another request by designers that goes beyond simple pattern settings. With the ability to change fill patterns or adjust the shading of layers, specific areas of the design can stand out more than they used to.
How the Tools Can Be Used
Task setups: PCB layout is characterized by certain tasks, such as footprint creation, component placement, and trace routing. Many of these tasks require specific parameters to be set up in order to use the full capabilities of the tools. For instance, trace routing can have many different manual and automated features to give the designer more options to work with. Although these tasks have traditionally had parameters to be set up, the amount of parameters continues to grow with each new enhancement that is added to the tools. Designers are requesting that these parameters be organized into one easy-to-access menu, as shown in OrCAD PCB Designer’s Parameter Editor below.
Functional setups: Along those same lines there will also need to be many more parameters for functions. These would include setting up design reports, manufacturing files, and test points--all of which need to be easily accessible and simple to work with.
Units, grids, and text: These are standard parameters that have been available for a long time but as the complexity of the tools continues to grow, so do the numbers of these settings. PCB designers have long requested that these setups be easy to find, work with, and able to be read in from templates or other sources.
Thankfully EDA vendors are responding to these requests from their users and most design tools are becoming easier to work with when setting up parameters for layout. Here is an example of how that is being done.
The Parameter Editor menu from OrCAD PCB Designer.
Setting up Layout Parameters in PCB Design CAD Tools
There are too many different parameters for PCB layout to discuss them all here, but we will highlight one that can be useful in Cadence’s OrCAD PCB Designer tools.
Having net names displayed in your layout on your traces, pads, vias, and areas of metal can be a very useful feature. It helps when searching for a specific net while working at a close range, and it is also very helpful during design reviews. At the same time, though, it loads up the screen with a lot of information that may not always be necessary. When you are editing the component placement or cleaning up the trace routing, you don’t always need the distraction of seeing each and every net name.
In OrCAD PCB Designer, you can easily turn the display of these net names on or off by using the design parameter editor menu. As you can see on the left side in the picture below, the nets are displayed on some traces and a pad. By toggling off the display of the net names, on the right side of the picture, the display is much cleaner for routing and editing. This is just one example of the way that OrCAD helps the user to be able to modify the parameters for PCB layout in order to customize the display and work environment to increase design productivity.
The Design Parameter Editor allows the user to toggle the display of net names on and off.
There are many ways that users can modify the design environment in Cadence tools, and the layout parameters are just one of those ways. To find out more about PCB layout, take a look at this E-book from Cadence.
If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.