Under the hood of a contemporary automotive vehicle
Not long ago, an amateur mechanic with the right tools and a maintenance manual could perform most car repairs. Times have changed, though. A look under the hood today is enough to discourage almost anyone.
Today’s complex and advanced automobiles—like autonomous vehicles (AVs) and electric vehicles (EVs)—contain more electronic systems and circuit boards. AV features, for example, include lane control, light detection and ranging (LIDAR), vehicle-to-vehicle (V2V) communication and collision avoidance system (CAS) hardware. Additionally, EVs require boards that process and operate at various voltage levels.
The engine compartment on newer vehicles displays another departure from older designs. New designs create new challenges, though. And PCBA functionality can be threatened by the extreme temperatures that engine compartments generate. Mechanical stress from vibrations and road debris can also disrupt PCBAs. Enclosures protect boards from these threats. Let’s take a look at how to best design an automotive PCB enclosure, which most often requires the integration of ECAD and MCAD.
PCBA ECAD and MCAD
It may seem as though circuit board design has always utilized software. A review of the history of printed circuit boards will quickly dispel this assumption. For decades, circuit boards were hand-drawn and manually crafted. The same is true for mechanical systems such as PCB enclosures. Designing boards and enclosures with ECAD and MCAD tools increases speed, accuracy and cost-effectiveness. However, ECAD and MCAD require a well-defined workflow to realize their benefits.
ECAD / MCAD Workflow
Circuit board designers for automotive systems must consider the mechanical enclosure that holds the board. When PCBAs require custom enclosures, a system design approach that includes ECAD and MCAD integration (ECAD-MCAD or ECAD/MCAD) is necessary. At its best, ECAD/MCAD is a collaborative effort where the PCBA designer and enclosure designer share data and information on each other’s process. Examples of this process shown below describe the ECAD/MCAD workflow.
Example of ECAD/MCAD workflows
As shown in the figure, ECAD/MCAD collaboration requires two software systems that operate on different data types to share information. The process is most effective if your PCBA design software supports seamless ECAD/MCAD with 3D import and export capabilities in formats such as .STEP, .OBJ, .STL, .DWG. Let’s examine how to best design an automotive PCB enclosure utilizing ECAD/MCAD.
Design Considerations for an Ideal Automotive PCB Enclosure
Ideally, automotive PCB enclosure design will reflect a collaborative effort between an electronic board designer and a mechanical designer. In practice, though, board designers are often required to assume both roles. However, design optimizations are still possible—provided designers have good guidelines.
Guidelines for Automotive PCB Enclosure Design
- Ensure the MCAD and ECAD tools utilize the same data format
- Select component packages that fit well within the enclosure
- Ensure the enclosure will accommodate board size
- Ensure board cutouts are aligned accurately with component placements
- Know the environmental hazards for the installation
- Consider effects on signal transmission
- Select enclosure material that meets thermal requirements
- Account for equipment tolerances
|Tempo's Custom AV & EV Automotive PCBA Manufacturing Service
Following the above guidelines can help ensure that your board will fit in the automotive PCB enclosure, function as designed and find protection from environmental threats.
At Tempo Automation, we specialize in building high-quality PCBAs for hazardous environments such as automotive systems.
To help you get started on the best path, we furnish information for your DFM checks and enable you to view and download DRC files. If you’re an Altium user, you can simply add these files to your PCB design software.
 Image from Stjepandic, Josip & Emmer, Christian & Fröhlich, Arnulf & Jäkel, Volker. (2014). Standardized Approach to ECAD/MCAD Collaboration. Journal of Aerospace Operations. 3. 10.3233/978-1-61499-440-4-587.