What are some best practices for PCB layout and routing for repairability?

1 Plan your schematic

Before you start laying out your PCB, you need to have a clear and detailed schematic of your circuit. A schematic is a graphical representation of the components, connections, and functions of your circuit. It helps you to organize your design, identify errors, and document your work. You should use a software tool that allows you to create, edit, and export your schematic in a standard format, such as SPICE or Eagle. You should also label your components, pins, nets, and values clearly and consistently, and use symbols and colors that are easy to recognize and follow.

2 Choose your components wisely

The components you choose for your PCB can have a significant impact on its repairability. You should select components that are compatible with your design goals, available in the market, and easy to solder and desolder. You should also avoid using components that are too small, fragile, or sensitive, as they can be difficult to handle and replace. For example, you should prefer through-hole components over surface-mount components, as they are easier to work with and more robust. You should also avoid using ball grid array (BGA) packages, as they require specialized equipment and skills to rework.

3 Optimize your board size and shape

The size and shape of your PCB can affect its functionality, stability, and repairability. You should optimize your board size and shape to fit your enclosure, minimize the number of layers, and reduce the amount of wasted space. You should also avoid using irregular or complex shapes, as they can complicate the fabrication and assembly process and increase the risk of mechanical stress and damage. You should use standard shapes, such as rectangles or circles, and round off the corners and edges to prevent sharp or protruding parts.

4 Minimize your trace length and width

The trace length and width are the dimensions of the copper tracks that connect the components on your PCB. They determine the electrical characteristics, such as resistance, capacitance, and inductance, of your circuit. You should minimize your trace length and width to reduce the signal loss, noise, and interference, and improve the speed and efficiency of your circuit. You should also avoid using long or thin traces, as they can increase the heat dissipation and the risk of breakage. You should use short and wide traces, and follow the recommended guidelines for your specific application and frequency range.

5 Follow the design rules

The design rules are the specifications and constraints that govern the fabrication and assembly of your PCB. They include parameters such as clearance, spacing, alignment, hole size, pad size, via size, and solder mask. You should follow the design rules to ensure that your PCB meets the quality and performance standards, and avoids errors and defects. You should also check your design for compliance with the design rules before sending it to the manufacturer, using a software tool that can perform a design rule check (DRC). You should also verify your design with a prototype or a test board before mass production.

6 Add test points and labels

Test points and labels are features that help you to access, measure, and debug your circuit. Test points are exposed pads or holes that allow you to connect probes, clips, or wires to specific points on your PCB. Labels are text or symbols that identify the components, pins, nets, and values on your PCB. You should add test points and labels to your PCB to facilitate the testing, diagnosis, and repair of your circuit. You should place test points near critical or problematic components or signals, and use standard conventions for labeling them. You should also use clear and consistent fonts and colors for your labels, and avoid covering them with components or solder mask.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?