What are the most common design-for-manufacturing guidelines for PCBs?

1 Choose the right PCB materials

The first step in designing a PCB is to select the appropriate materials for your application and specifications. The most common PCB material is FR-4, a composite of glass fiber and epoxy resin, which offers good mechanical and electrical properties, as well as low cost and availability. However, depending on your requirements, you may need to consider other materials, such as ceramic, metal core, or flexible substrates, which have different characteristics and advantages. For example, ceramic PCBs have high thermal conductivity and low coefficient of thermal expansion, which make them suitable for high-power and high-frequency applications. Flexible PCBs, on the other hand, can bend and conform to different shapes and sizes, which make them ideal for wearable and portable devices.

2 Minimize the number and size of vias

Vias are holes in the PCB that connect different layers of copper traces. They are essential for routing complex circuits, but they also introduce some challenges and limitations for the fabrication and assembly processes. Vias increase the complexity and cost of drilling, plating, and soldering, as well as the risk of defects and failures. Therefore, you should try to minimize the number and size of vias in your PCB design, as well as avoid placing them in critical areas, such as pads, traces, or components. You should also use the appropriate type of via for your design, such as through-hole, blind, or buried vias, depending on the number of layers and the density of your PCB.

3 Follow the design rules and constraints

Design rules and constraints are parameters that define the minimum and maximum values for various features and elements of your PCB layout, such as trace width, spacing, clearance, pad size, drill size, and so on. These rules and constraints are determined by the capabilities and limitations of the fabrication and assembly equipment, as well as by the standards and specifications of your industry and application. By following the design rules and constraints, you can ensure that your PCB can be manufactured and assembled without errors or defects, as well as meet the performance and reliability requirements. You can use the design rule check (DRC) tool in your PCB design software to verify and validate your layout against the design rules and constraints.

4 Optimize the component placement and orientation

The component placement and orientation on your PCB can have a significant impact on the functionality and performance of your circuit, as well as on the ease and efficiency of the assembly process. You should place the components in a logical and orderly manner, according to their function, signal flow, and interconnection. You should also orient the components in a consistent and uniform way, preferably with the same polarity and direction, to avoid confusion and errors during the soldering and inspection stages. Additionally, you should leave enough space and clearance between the components and the board edges, as well as avoid placing components on both sides of the board, unless necessary, to reduce the complexity and cost of the assembly process.

5 Use standard and common components

One of the ways to reduce the cost and time of your PCB project is to use standard and common components, rather than custom or exotic ones. Standard and common components are those that have widely available and compatible specifications, sizes, shapes, and packages, which make them easier to source, order, and assemble. They also have lower prices and higher quality, as they are produced in large quantities and undergo rigorous testing and quality control. By using standard and common components, you can also simplify your inventory management and reduce the risk of obsolescence and shortages. You can use online databases and catalogs to find and compare standard and common components for your PCB design.

6 Include test points and fiducials

Test points and fiducials are features that help you test and troubleshoot your PCB, as well as align and position it during the fabrication and assembly processes. Test points are pads or holes that expose specific points or nodes of your circuit, where you can attach probes or clips to measure voltage, current, resistance, or other parameters. Fiducials are marks or dots that provide reference points for the alignment and registration of the PCB layers, as well as for the placement and orientation of the components. By including test points and fiducials in your PCB design, you can improve the accuracy and efficiency of the manufacturing and assembly processes, as well as the quality and reliability of your PCB.