There are many different types of printed circuit boards (PCBs) you might use in your application, and rigid PCBs are one of the most common. These boards are stiff and durable, making them ideal for applications involving minimal motion.
This brief guide will explain the benefits, applications and key considerations of rigid PCBs so you can ensure your design works for your application.
What Are Rigid PCBs Used For?
Rigid PCBs are highly versatile for applications where movement is minimal. Some examples of common rigid PCB uses include:
Consumer technology: Rigid PCBs are robust and suitable for use in computer motherboards, especially in desktop computers that remain stationary most of the time.
Industrial equipment: Manufacturing plants and other industrial facilities can use rigid PCBs in automation controllers, robotic equipment and other machinery to enhance
Home appliances: LED lights, refrigerators and air conditioning systems might use a rigid PCB to power a consumer’s household.
Automotive technology: Internal components like engine control units (ECUs) and airbag systems rely on rigid PCBs to provide the required power for timely activation.
Medical devices: Diagnostic equipment such as MRI machines and larger wearable health monitors can benefit from the robustness and reliability of a rigid PCB.
Common Rigid PCB Materials
Rigid PCBs are composed of several different materials:
Base material: Also known as the substrate, the board’s base material is typically made from a rigid fiberglass substrate that incorporates an FR-4 flame retardant. FR-4 is a highly durable laminate made from woven fiberglass and epoxy resin, which gives the board structural stability, heat resistance and self-extinguishing capabilities.
Conductive materials: The board’s electronic components — traces and pads — are typically made from copper for high conductivity.
Solder mask: The solder mask is a layer of melted metal alloy that both attaches the electronic components to the circuit board and serves as insulation for the substrate and copper conductors.
Silkscreen: The silkscreen is a layer of ink traces that are applied on top of the solder layer to communicate vital information about the board to individuals who need to service or test it. Manufacturers can also add branded visuals to the silkscreen to create a more cohesive appearance.
Key Considerations in Rigid PCB Design
The number of layers a board has is a significant factor in layout and design:
Single-sided rigid PCBs: These simple boards are well-suited for rapid production requirements because they are simple and easy to manufacture.
Double-sided rigid PCBs: Double-sided circuit boards are an industry standard. They are very similar to single-sided rigid PCBs, except that they have copper traces on both sides. The circuits on one side of the board connect to circuits on the other side using through-hole technology and/or surface-mount technology.
Multilayer PCBs: Multilayer PCBs have more than two conductive layers, each separated by insulation. These boards allow for complex designs. The extra layers can help prevent electromagnetic interference generated from the device.
Factors Contributing to Rigid PCB Complexity
A rigid PCB’s design can be as simple or as complex as needed to integrate into your application. For example, a bare rigid PCB can help you save valuable time and effort by prototyping various board configurations before adding the electronic components.
Some of the most important design factors that contribute to a circuit board’s complexity include:
Number of layers: The more layers added to a circuit board, the more complex it becomes.
Component density: A component-dense part of a PCB contains many electronic components, which helps you save space and reduce assembly costs.
Signal integrity: A complex board is typically more able to maintain a strong signal without interference because it contains more channels for the signal to travel through.
Thermal management: Generally, the more insulation you add to a PCB, the more complex it will become. Insulation typically comes in the form of extra layers or more robust, which can increase the board’s functionality.
Design for manufacturability (DFM): Designing a board specifically for manufacturability helps you minimize production costs and boost manufacturing efficiency. However, it may require you to simplify your original design.
What Are the Benefits of Complex PCBs?
Increasing the complexity of a board design can greatly benefit your application in several ways:
Compact footprint: Complex PCBs can pack more functionality into a single board than simpler designs, which reduces the need to use multiple separate boards for the same applications. Dense multilayer designs allow you to minimize the board’s size and weight, making it better suited to small devices like wearables and smartphones.
Advanced signal processing: Complex PCBs are highly effective at maintaining signal integrity and reducing interference, enabling them to manage high-frequency signals more easily than simple boards.
Increased versatility: Increasing a rigid PCB’s complexity gives you greater design flexibility by allowing you to design a solution that is completely tailored to your application.
Cost-effectiveness: By integrating more functionalities into one board, you can reduce assembly costs and increase production efficiency.
Contrast Between Rigid vs. Flex PCBs
Two of the key differences between rigid and flex PCBs include their basic structure and the most suitable applications for each type.
Rigid PCBs are constructed from an inflexible base of fiberglass or ceramic. These materials provide excellent structural stability and durability by limiting board flexibility, which supports the electronic components for high-volume production.
In contrast, flexible PCBs are much lighter and can withstand greater ranges of movement. Because they can be twisted and bent to fit various environments, they work well in irregular spaces and devices where space is limited.
Applications and Use Cases
Rigid PCBs are best suited to fixed applications where the device either remains stationary or has a limited range of motion. Manufacturing equipment and medical machinery are strong examples of applications for rigid PCBs.
Flexible PCBs, on the other hand, are better for dynamic applications that require a greater range of motion. Because flex PCBs can bend and withstand greater mechanical stress than rigid PCBs, they’re good for mobile devices and wearables that conform to the body’s shape.
Rigid-flex PCBs combine both board types into one unit by attaching a flexible strip board to a rigid component. These boards are best for applications where they will undergo extreme conditions, such as in avionics and aircraft navigation systems.
Let Via Technology Inc. Handle Your Rigid PCB Needs
Since 1993, we’ve helped businesses like yours design, assemble and manufacture printed circuit boards to suit any application. Whether your application requires a bare PCB for prototyping or a fully assembled rigid PCB, we can help you get the board you need.
