Highly computerized electric vehicles utilize several circuit technologies to power everything from dashboard controls to charging units. The printed circuit boards, flexible printed circuits, and flexible heaters used in these vehicles have the same base design as those used in internal combustion engine automotive vehicles. However, the operating environment of electric vehicles presents unique challenges when designing your circuits.
Powering Sophisticated Computer Systems
Electric vehicles require power to operate numerous specialized systems, such as motor control units, Battery Management Systems, and onboard chargers. Due to these factors, automotive PCB assemblies used in these applications must be designed to handle higher voltages.
High-Power and Low-Power Automotive Printed Circuit Boards
For trace width and spacing for high-voltage systems, you may assume that a .015” wide trace at 1 oz copper thickness can handle 1 amp of current sufficiently. However, it’s best to overdesign in this area to accommodate automotive margins of safety.
Plating thickness is typically 1 oz (1.4 mils). If more is required for the power circuits, this should be calculated for the amount of current transferring through the plated holes.
Battery Management Systems
Battery systems, including temperature sensors and weld tabs, are typical. Multi-layer PCBs designed for thermal stability and with high-current handling capabilities are critical to these systems. Weld tab sizes should be detailed accurately to accommodate your tools and fixtures.
Advantages of Flexible Circuits in Automotive Applications
There are benefits to using flexible circuit assemblies in electric vehicles. The first and most beneficial is the ability to wrap circuits around contours or route them through complex wiring systems. Weight reduction is also achieved due to the lightweight materials used. Further, flexible circuits offer superior shock and vibration resistance and can replace wire cable harnesses, resulting in a cleaner automotive PCB assembly.
In more dynamic applications, a rigid-flex automotive PCB assembly is the preferred choice. The hybrid design combines the benefit of secure component mounting with the flexibility of polyimide, eliminating connectors and reducing assembly time.
Preparing for Submission and Final Design Considerations
A thorough Design for Manufacturability (DFM) assessment is critical before sending design files to your fabricator. When designing an automotive PCB assembly for use in electric vehicles, consider the following:
- Thermal shock: Will your assembly require stress-relief measures or a conformal coat to support thermal shock testing?
- Vibration: Will your assembly require stress-relief measures or a conformal coat to support vibration testing?
- Humidity: Will your assembly require a conformal coating or a specialty coating to withstand the humidity expected in typical use?
Additionally, the design should comply with IATF 16949 and any other applicable automotive standards. Please reference our printed circuit board design checklist for additional factors to consider before submitting your automotive PCB assembly design for fabrication.
Design Considerations for PCBs in Electric Vehicles: The Final Word
Working with an experienced automotive PCB manufacturer will be valuable throughout the design, prototype, and production stages of your product. It is important that they are familiar with and have experience fabricating and assembling automotive circuits. The experts at Tramonto Circuits have expertise across all transportation and automotive applications and can support you through all stages of production.
Send a message to discuss your electric vehicle PCB design with an engineer!