A large percentage of PCB design involves the layout of circuit boards for computers, mobile technologies, IoT, and a host of other devices used in various consumer applications. However, there is also a wide range of industrial applications that aren’t nearly as flashy or popular as the next generation of smartphones, which also need PCB designs. While the different technology types of circuit board layout are mostly the same, there are a few differences between them that demand special attention from PCB layout designers.
Industrial circuit boards are typically used in applications that require high power levels to drive motors or other heavy-duty equipment. Because of these power requirements, the layout rules and constraints are different than what would be used to layout a low-power IoT device. Here we’ll look at some of the differences with this type of circuit board layout technology and what designers need to understand about industrial PCB design rules.
Considerations for Circuit Boards in Industrial Applications
As with any PCB design, engineers must create the layout to produce a high-quality circuit board that can be efficiently manufactured for the best return on investment. However, there are some key considerations to consider when laying out industrial boards.
Design for power
Circuit boards for industrial applications are typically high-powered designs for use in motor control systems, power management equipment, automated robotic manufacturing, and similar devices. These applications monitor and control high power levels but may also employ sensitive low-power circuitry for their control systems. PCB layout designers working on these systems need to understand all of these power requirements to produce the highest-quality designs that can be safely operated.
Design for durability and longevity
Industrial applications also require rugged designs with a long lifecycle to reduce expensive machine downtime or the continual need to enhance and update critical-path equipment. To do this requires robust, high-quality circuit boards that are designed to withstand the stressful environments in which they will be operating. Circuit board designers must choose the best PCB components for these layouts and adhere to the appropriate design rules and constraints.
Design for certification
PCBs designed for industrial applications also may require manufacturers that carry certifications in specific industry standards. These certifications can include everything from the basic ISO 9001 to UL 508A for building enclosures and sub-panels that contain motor controllers, overload relays, and fused disconnect switches. PCB designers need to understand the specific certification requirements needed for their designs to be appropriately certified.
Next, we’ll look more specifically at some PCB layout rules that a designer should consider when laying out an industrial circuit board.
Industrial PCB Design Rules for High Power Circuits
To lay out a circuit board that can handle the increased power and life cycle requirements of an industrial PCB, designers need to build their design rules and constraints around the following:
- Thermal considerations: The increased power requirements of many industrial PCBs will result in more heat being conducted throughout the board. The layout needs to be designed for good airflow, and heat-generating components should be given plenty of space to those parts that are heat sensitive. Full power and ground planes will help with heat dissipation throughout the board layer stackup along with thermal vias to conduct heat away from hot components. Additional high-temperature measures may also be required, including heat sinks, thermal epoxy, and fans.
- Power integrity: Large current spikes or voltages swings in high-power circuit boards can create interference for sensitive circuits in the design. The power delivery network (PDN) needs to be designed keeping this in mind. Sensitive circuits should be kept isolated from power components, and multiple power supply circuits should be spread out as evenly as possible to help with thermal balancing. Power traces should be as short and wide as possible to lower their inductance to reduce noise introduced into the design.
- High-voltage: Industrial PCBs conducting high-voltages must be designed with adequate clearances between metal to prevent arcing from one conductor to another and are measured in two different ways. “Clearance” is the line-of-sight distance between the conductors, while “creepage” is the distance between the conductors across the physical contours of the board. Any high-voltage arcing could damage the board and its components without adequate spacing, eventually becoming a complete dead short, resulting in circuit performance problems or outright failure.
To ensure that these design considerations are accounted for in an industrial PCB layout, designers should load their CAD tools with as many design rules and constraints as possible. These design rules will allow them to maintain the proper clearances between components and metal objects and hold the desired trace widths for power circuitry. But the list of design considerations isn’t finished yet as some design for manufacturability (DFM) rules still need to be considered.
Manufacturing Considerations for Industrial PCB Designs
Not only does a circuit board need a symmetrical layer stackup with power and ground planes for thermal balancing and power integrity, but it is also essential to prevent board warpage during manufacturing. The configuration of the board layer stackup is also influenced by the needs of the PDN for good signal integrity and what kind of board materials are used in high-voltage designs. It is also important to use a good board surface finish to protect the assembly process during manufacturing. A conformal coating will also add another insulation layer to help prevent high-voltage arcing.
Many fabrication and assembly details like this must be decided on to build the best industrial circuit possible, and thankfully, a good PCB contract manufacturer like VSE can help. At VSE, we’ve partnered with our industrial circuit board customers to build the highest quality designs possible for over 35 years, and we understand the needs and requirements you face. We are ISO 9001, and UL 508A certified and are fully set up and staffed to help you with your next industrial printed circuit board project.
