Precision Tools for ECAD-MCAD Co-Design of Multi-Board PCBs

November 20, 2019 Cadence PCB Solutions

Picture of the 9 transistor Holiday radio

 

I still have the “Holiday 9 Transistor” radio from the late 1950’s that belonged to my Grandfather. With its brown leather case accented by two cutouts for the on/off volume and frequency dials, it brings back many memories. Classified on social media as “vintage,” it hasn’t been used in over 30 years. Yet surprisingly when I popped a battery into it for this picture, it still worked. They really don’t make them like they used to.

Primitive by today’s standards, this radio features a simple circuit board with thru-hole component leads soldered together on the back side of the board. Electronics like this typically had only one circuit board in them, and plenty of room for everything to fit within the plastic enclosure of the radio. That’s not the case anymore however as modern electronics can have multiple circuit boards and flex circuits packed tightly within them.

To create these complex electronics takes careful planning and meticulous attention to detail. No longer do designers have the luxury of spare room to casually fit everything in. Instead, both the mechanical and electrical aspects of the design must be created together in order to ensure their compatibility. Let’s take a look at the processes and the tools required for successful ECAD-MCAD co-design of multi-board PCBs.

What is ECAD-MCAD Co-Design of Multi-Board PCBs?

To keep up with the increasingly complex design demands of today’s electronics, PCB designers are having to incorporate new technologies and processes into their design workflows. One such example is the combination of both electrical and mechanical design of multiple system boards within the same PCB design CAD tool.

Traditionally, system design involved developing each printed circuit board individually, while the mechanical engineering team was creating the system enclosure. For systems with multiple circuit boards, each board was designed and prototyped individually. Once the boards were verified to run correctly, the boards and the system enclosure would be brought together where the testing of the entire system would begin. 

While the circuit boards had been verified individually during their initial testing, new problems were often found when interfacing with the rest of the system electronics or mechanical design. This would ultimately force another re-design of the affected boards to iron out these problems.

Designers no longer have the luxury of going through lengthy and costly redesign cycles and prototype builds in order to work the bugs out of the system, especially when multiple circuit boards are involved. Electrical CAD and mechanical CAD co-design tools give the designer the ability to find and correct many of these problems before going through PCB and mechanical prototype builds. 

PCB designers can see the effect their parts placement will have on the mechanical design, as well as how the electrical connectivity between the boards matches up. Finally, using advanced ECAD-MCAD co-design tools, they can fold all of the multi-board PCBs virtually into the mechanical enclosure to verify the fit and function of the entire system. If this sounds too good to be true, hold on, there’s more.

 

Picture of a technician working on the multiple boards of a laptop

ECAD-MCAD co-design tools can help with multi-board system design like this laptop

 

The Benefits of a Multi-Board PCB Design Flow

In the old traditional system design workflow, the different printed circuit boards of the system would be developed as individual projects. When all of the PCB designs of the system were completed, they would then have to be tested altogether in order to verify system operation and compatibility. Some of the purposes for these tests included:

 

  • All the circuit boards would be connected together in order to verify that the system worked as it was designed to.

  • Individual PCB design details would have to be looked at for system compatibility, such as the pinouts of intra board connectors to make sure that the wiring harnesses correctly connected one board to another.

  • Connectors, switches, and other human interfaces would be verified for easy accessible once all the system boards were assembled together.

  • All PCB designs would have to be confirmed to be at the same version, and that there weren’t any changes made to one design that hadn’t been incorporated into the others.

 

Although these concerns wouldn’t be problems for each individual PCB design, they do become very important when all the circuit boards are brought together in the mechanical enclosure of the system. And here is where ECAD-MCAD co-design tools can really help.

By bringing all the different system boards and the mechanical design into one design environment, PCB designers can virtually simulate the concerns listed above instead of building a prototype. They can confirm in a 3D environment that each board connects correctly to the rest of the system, that all connectors and interfaces are accessible, and that all portions of the design are at the same version as the rest. 

For successful ECAD-MCAD collaboration however, there must be several essential factors in place first. These include starting with a plan for engineering prototyping workflow management and addressing form factors in multi-board circuits. Additionally, the PCB designer should take into account the multi-board PCB edge clearances all the way through design by utilizing all the tools available such as the PCB design grid.

 

Picture of a circuit board with many cables and wiring harnesses attached to it

One of the key advantages of ECAD-MCAD co-design tools is verifying interface accessibility 

 

Additional Information on ECAD-MCAD Co-Design of Multi-Board PCBs

To make ECAD-MCAD co-design of multi-board PCBs a design success for you, here are some important points that you should consider.

The Key is MCAD/ECAD Collaboration

As we have been talking about, a successful ECAD-MCAD co-design environment can save a lot of time and money by reducing the amount of redesigns and prototype builds that you will need. But there are some important requirements that you need to observe in order to achieve this starting with the type of tools that you are working with. It is imperative that the CAD systems that you are using have the ability to seamlessly communicate bi-directionaly with each other in order to transfer data between them. Without this you will be fighting with trying to read and write data in order to synchronize it between tools.

 

Here is more about MCAD-ECAD Collaboration.

Start the Job Right with Engineering Prototyping Workflow Management

Once you have the tools in place to do the job, you need a plan. Without a workflow process in place before you begin, you may end up wasting as much time as you did with your older and more traditional system design workflows. You need to develop your engineering workflow for prototyping multi-board system design before you start the design. This way you can minimize the possibility of wasting time by identifying any potential problem areas of your workflow before you begin.

 

Try  this for more information on engineering prototyping workflow management.

 

Picture of 3D layout of a multi-board assembly

Advanced ECAD-MCAD co-design tools are essential for multi-board PCBs like this

 

Utilize MCAD & ECAD in Addressing Form Factor in Multi-Board Circuits

Working with the advanced tools required for MCAD and ECAD multi-board design will require a new set of design skills and tool savvy. These tools will give you the ability to create and work with 3D component models, work with imported 3D mechanical models of cases or enclosures, and perform 3D collision checks for your components, the boards, and the system enclosure. To maximize the effectiveness of the tools, you will need to be able to work as smoothly as possible with these features in order to rapidly move your design into production.

 

Here is further reading on addressing form factors in multi-board circuits.

ECAD-MCAD Confirmation of Multi-Board PCB Edge Clearance

Using your 3D ECAD-MCAD tools for system level design also extends to making sure that these designs are manufacturable. As with any PCB, your system boards will have to be manufactured on a panel and then successfully removed from it. Your design needs to make sure that there is sufficient clearance between the components and the edges of the boards that they are mounted on to facilitate breaking the boards out of their panels. Without these clearances your manufacturing costs may go up, or you may have to redesign the board.

 

This will help you to find out more on multi-board PCB edge clearances.

The PCB Design Grid is Your Friend

There are a number of features and functions available to you in today’s advanced PCB design tools, and by leveraging them you can help your design efforts. One of these is the good ol’ standard design grid. Especially when working with multiple board designs where pairing up mating connectors is critical, it is important to use the design grid to locate your connectors precisely where you want them.

 

Look here to find further reading on using PCB design grids.

 

Screenshot of 3D layout with and without a covering case

Being able to move mechanical objects aside is a key benefit of 3D ECAD-MCAD tools

 

For the Best Multi-Board Designs You Need the Best ECAD-MCAD Co-Design Tools

There are many PCB design systems that offer different levels of co-design capability. To create the best though, you need the best. You need design software that can handle multiple PCB designs and 3D mechanical models simultaneously. You need tools that will give you the ability to interact with these important designs and models, so that you can move them in and out and maneuver them as required. You also need powerful 3D capabilities that will show you the design as it will truly appear, and will also report back to you DRC collisions and other system level problems.

The advanced PCB design tools that you need for ECAD-MCAD co-design of multi-board PCBs is already available and on the market today. Allegro PCB Designer from the Cadence line of premium EDA tools is the design system that you need to support your multi-board design needs. With the features and capabilities that we’ve been talking about, Allegro can make the difference between getting your system design up and running and ready for market before the rest of your competitors.

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts

About the Author

Cadence PCB solutions is a complete front to back design tool to enable fast and efficient product creation. Cadence enables users accurately shorten design cycles to hand off to manufacturing through modern, IPC-2581 industry standard.

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