MCAD-ECAD Co-design

A common component library aids engineering integration.

As I mentioned in my column last month, PCB design best practices have five pillars. The first pillar, digitally integrated and optimized, is the foundation. It specifically addresses interactions within the design process and how multidiscipline and multidomain integration and collaboration should take place.

This leads me to pose a simple question: Is your engineering team digitally integrated and optimized when it comes to MCAD-ECAD co-design, or is it functioning with a legacy approach that contains many manual efforts/tasks while team members are working in silos?

Every PCB design starts with the design of the physical package/box (the system) where the PCB will reside. As this occurs, the physical features of the PCB are defined. These features include items such as the dimensions of the PCB outline; board thickness; mounting holes; tooling holes; restricted areas/rooms such as specific components’ height ceilings; component keep-ins and keep-outs; critical components such as connectors, heatsinks and sub-assemblies; plus any other pertinent critical features and or details.

While the mechanical engineer is addressing the mechanical/physical aspects of the system, the electrical engineer is doing their part addressing the electrical requirements of this system. This includes the creation of the required circuits that ultimately define the electrical schematic.

Historically, several issues hampered cross-domain collaboration. The different domains had completely different tools, different user specialties, different languages/terms for communication, and different databases. This made it difficult to communicate changes while both domains proceeded in parallel and worked in silos – the best that could be expected was email, drawings on post-it notes, or in-person verbal direction. The struggle with the handoff between electrical and mechanical disciplines within the legacy methodologies lies in this manual approach and can be error-prone. There is inefficiency and a lack of instant bidirectional communication when addressing these legacy data exchange formats.

The industry has evolved, providing a digital thread in the form of industry standard data exchange formats. Decades ago, DxFs became a common way to pass graphical data, but the information was very limited (often 2-D, with no intelligence about objects, thus requiring interpretation) so they were typically only used in a one-way path from MCAD to ECAD. STEP enabled more 3-D intelligence, including enclosures. IDF was constructed for bidirectional collaboration, but transferred the entire database without any tracking to identify changes. Incremental Design Exchange (IDX) brought the ability to send incremental changes and traceability.

The IDX format is the latest and greatest format for MCAD-ECAD co-design. This format enables a more efficient, unified collaboration workflow. It allows designers to accept or reject any proposed items sent from the other domain. To keep data synchronized, every proposal comes with a response from the other domain. This helps users to understand the current status of the board within both mechanical and electrical domains to ensure they stay in sync with each other. This also makes it much easier to address problems as they are encountered, rather than undertaking a long review at the end of the design process and updating or correcting the project after it is complete. 

It must be noted that even tighter integrations are possible. A model-driven approach, with both MCAD and ECAD sharing the same component library, has the potential to save significant library creation time and ensure that all of engineering is on the same page. Today’s 3-D ECAD design tools enable layout designers to view what the mechanical engineer is working on without leaving their native environment and verify their design in that context. Likewise, PCB data down to the trace and via level helps the mechanical engineer accurately model and simulate the board in their environment.

A number of analysis tools available validate the digital twin before prototype. Ideally, these tools work directly off the ECAD or MCAD authoring database (a high-fidelity digital twin) to minimize rework. While adopting these tools sounds like extra work, it’s been proven that “virtual prototyping” (analysis and verification during design) saves significant time and cost through re-spin reduction.

When we look at the complexity of today’s electronic system design, legacy processes created decades ago and still being deployed don’t fully meet today’s needs nor do they fully address the challenges and problems engineering teams face. The industry addressed this with the evolution of the IDX standard.

The value we get from a digitally integrated and optimized MCAD-ECAD co-design process is a streamlined approach that contains multidiscipline and multidomain integration and collaboration, which minimizes risks during the ECAD-MCAD data exchange throughout the PCB design process.

Stephen Chavez is a senior printed circuit engineer with three decades’ experience. In his current role as a senior product marketing manager with Siemens EDA, his focus is on developing methodologies that assist customers in adopting a strategy for resilience and integrating the design-to-source Intelligence insights from Supplyframe into design for resilience. He is an IPC Certified Master Instructor Trainer (MIT) for PCB design, IPC CID+, and a Certified Printed Circuit Designer (CPCD). He is chairman of the Printed Circuit Engineering Association (PCEA); stephen.chavez@siemens.com.