Introduction

OrCAD is one of the most widely used software tools for designing printed circuit boards (PCBs). Developed by Cadence Design Systems, OrCAD offers a comprehensive suite of tools for schematic capture, PCB layout, and simulation, making it a popular choice among engineers and designers. Whether you’re a beginner or an experienced professional, this tutorial will guide you through the process of designing a PCB using OrCAD, from creating a schematic to generating manufacturing files.

Getting Started with OrCAD

1. Installation and Setup

Before you can start designing PCBs with OrCAD, you’ll need to install the software. Follow these steps to install and set up OrCAD:

1. Download the Software: Visit the Cadence website and download the OrCAD software. You may need to create an account and purchase a license, or you can download a free trial version.
2. Install the Software: Run the installer and follow the on-screen instructions to install OrCAD on your computer. Make sure to install all necessary components, including the OrCAD Capture CIS for schematic design and the OrCAD PCB Designer for PCB layout.
3. License Activation: After installation, activate your license using the license key provided by Cadence. If you’re using a trial version, follow the instructions to activate the trial period.
4. Configure Settings: Once the software is installed, configure the settings according to your preferences. This includes setting up library paths, grid settings, and default preferences for schematic and PCB design.

2. Understanding the OrCAD Interface

Before diving into PCB design, it’s essential to familiarize yourself with the OrCAD interface. The main components of the OrCAD interface include:

1. Project Manager: The Project Manager is where you create and manage your projects. It allows you to organize your design files, including schematics, PCB layouts, and libraries.
2. Schematic Capture: The Schematic Capture tool is used to create and edit schematic diagrams. It provides a graphical interface for placing components, drawing connections, and annotating your design.
3. PCB Editor: The PCB Editor is used to create and edit PCB layouts. It provides tools for placing components, routing traces, and defining board outlines.
4. Library Manager: The Library Manager is used to create and manage component libraries. It allows you to add, edit, and organize components for use in your designs.
5. Simulation Tools: OrCAD includes simulation tools for analyzing the performance of your design. These tools include PSpice for circuit simulation and Signal Integrity for analyzing signal integrity issues.

Creating a Schematic in OrCAD

1. Starting a New Project

To start a new project in OrCAD, follow these steps:

1. Open OrCAD Capture: Launch OrCAD Capture from the Start menu or desktop shortcut.
2. Create a New Project: In the Project Manager, click on “File” > “New” > “Project”. Choose “Schematic” as the project type and give your project a name. Select the location where you want to save your project and click “OK”.
3. Add Schematic Pages: In the Project Manager, right-click on the “Design Resources” folder and select “New Schematic”. This will create a new schematic page where you can start placing components.

2. Placing Components

To place components on your schematic, follow these steps:

1. Open the Component Library: In the Schematic Capture tool, click on “Place” > “Part” to open the component library. You can browse through the available libraries or search for specific components.
2. Place Components: Select the components you need and place them on the schematic page. You can rotate and move components as needed by right-clicking and selecting the appropriate options.
3. Connect Components: Use the “Place Wire” tool to draw connections between components. Click on the pins of the components to start and end the wires. You can also use the “Place Net Alias” tool to label nets for easier identification.

3. Annotating the Schematic

Annotating your schematic involves assigning unique reference designators to each component. This is important for ensuring that your design is organized and easy to understand.

1. Auto-Annotate: In the Schematic Capture tool, click on “Tools” > “Annotate” to open the Annotate dialog box. Choose the “Incremental Reference Update” option and click “OK”. This will automatically assign reference designators to your components.
2. Manual Annotation: If you need to manually annotate components, you can do so by double-clicking on the reference designator and entering a new value.

4. Adding Footprints

Footprints define the physical layout of components on the PCB. To add footprints to your components, follow these steps:

1. Open the Component Properties: Double-click on a component to open its properties dialog box.
2. Assign Footprints: In the properties dialog box, go to the “PCB Footprint” tab and enter the footprint name. You can browse through the available footprints in the library or enter a custom footprint name.
3. Verify Footprints: After assigning footprints, verify that all components have the correct footprints assigned. You can do this by reviewing the properties of each component.

5. Running a Design Rule Check (DRC)

Before moving on to PCB layout, it’s important to run a Design Rule Check (DRC) to ensure that your schematic is free of errors.

1. Run DRC: In the Schematic Capture tool, click on “Tools” > “Design Rules Check” to open the DRC dialog box. Select the options you want to check and click “OK”.
2. Review Errors: If any errors are found, review the error report and make the necessary corrections to your schematic.

Creating a PCB Layout in OrCAD

1. Starting a New PCB Layout

To start a new PCB layout in OrCAD, follow these steps:

1. Open OrCAD PCB Designer: Launch OrCAD PCB Designer from the Start menu or desktop shortcut.
2. Create a New Board: In the PCB Editor, click on “File” > “New” > “Board” to create a new PCB layout. Give your board a name and select the location where you want to save it.
3. Import Netlist: In the PCB Editor, click on “File” > “Import” > “Netlist” to import the netlist from your schematic. Select the netlist file generated from your schematic and click “OK”.

2. Setting Up the Board Outline

The board outline defines the physical dimensions of your PCB. To set up the board outline, follow these steps:

1. Draw the Board Outline: In the PCB Editor, use the “Shape” tool to draw the board outline. You can draw rectangular, circular, or custom-shaped outlines depending on your design requirements.
2. Define Keep-Out Areas: Use the “Keep-Out” tool to define areas where components and traces cannot be placed. This is important for ensuring that your design meets mechanical and electrical constraints.

3. Placing Components

To place components on your PCB, follow these steps:

1. Auto-Place Components: In the PCB Editor, click on “Place” > “Auto-Place” to automatically place components on the board. You can choose different placement strategies, such as “Cluster Placer” or “Statistical Placer”.
2. Manual Placement: If you need to manually place components, use the “Move” tool to drag and drop components to their desired locations. You can rotate and flip components as needed.
3. Align and Distribute Components: Use the “Align” and “Distribute” tools to ensure that components are evenly spaced and aligned. This is important for achieving a clean and organized layout.

4. Routing Traces

Routing traces involves connecting the pins of components with copper traces. To route traces in OrCAD, follow these steps:

1. Auto-Route Traces: In the PCB Editor, click on “Route” > “Auto-Route” to automatically route traces on the board. You can choose different routing strategies, such as “Fanout”, “Route”, and “Cleanup”.
2. Manual Routing: If you need to manually route traces, use the “Add Connect” tool to draw traces between component pins. You can adjust the width and layer of the traces as needed.
3. Differential Pair Routing: For high-speed designs, use the “Differential Pair” tool to route differential pairs. This ensures that the pairs are routed together with consistent spacing and length.

5. Adding Vias and Planes

Vias and planes are used to connect different layers of the PCB and provide power and ground connections. To add vias and planes, follow these steps:

1. Add Vias: Use the “Add Via” tool to place vias on the board. Vias can be through-hole, blind, or buried, depending on your design requirements.
2. Add Planes: Use the “Shape” tool to add power and ground planes. Define the net for each plane and ensure that they are connected to the appropriate pins.

6. Running a Design Rule Check (DRC)

Before finalizing your PCB layout, it’s important to run a Design Rule Check (DRC) to ensure that your design meets all constraints and requirements.

1. Run DRC: In the PCB Editor, click on “Tools” > “Design Rules Check” to open the DRC dialog box. Select the options you want to check and click “OK”.
2. Review Errors: If any errors are found, review the error report and make the necessary corrections to your layout.

7. Generating Manufacturing Files

Once your PCB layout is complete, you’ll need to generate manufacturing files to send to your PCB manufacturer. To generate manufacturing files in OrCAD, follow these steps:

1. Generate Gerber Files: In the PCB Editor, click on “File” > “Export” > “Gerber” to generate Gerber files. Select the layers you want to export and click “OK”.
2. Generate Drill Files: In the PCB Editor, click on “File” > “Export” > “Drill” to generate drill files. These files contain information about the holes and vias on your board.
3. Generate Bill of Materials (BOM): In the Schematic Capture tool, click on “Tools” > “Bill of Materials” to generate a BOM. This file lists all the components used in your design.
4. Generate Assembly Drawings: In the PCB Editor, click on “File” > “Export” > “Assembly” to generate assembly drawings. These drawings provide instructions for assembling the PCB.

Advanced Features and Tips

1. Using Design Templates

OrCAD allows you to create and use design templates to streamline the design process. Design templates can include predefined board outlines, layer stackups, and design rules.

1. Create a Template: To create a design template, set up a PCB layout with your preferred settings and save it as a template file.
2. Use a Template: When starting a new project, you can select a design template to apply your predefined settings.

2. Simulating Your Design

OrCAD includes simulation tools that allow you to analyze the performance of your design before manufacturing. These tools include PSpice for circuit simulation and Signal Integrity for analyzing signal integrity issues.

1. Run PSpice Simulation: In the Schematic Capture tool, click on “PSpice” > “Run” to run a circuit simulation. Analyze the results to ensure that your design meets performance requirements.
2. Run Signal Integrity Analysis: In the PCB Editor, click on “Analyze” > “Signal Integrity” to run a signal integrity analysis. This helps identify and resolve issues such as crosstalk and signal reflections.

3. Using Design Reuse

OrCAD allows you to reuse design elements, such as schematic blocks and PCB modules, to save time and ensure consistency across projects.

1. Create a Reusable Block: In the Schematic Capture tool, create a schematic block that you want to reuse. Save it as a reusable block file.
2. Use a Reusable Block: When working on a new project, you can insert the reusable block into your schematic or PCB layout.

4. Collaborating with Team Members

OrCAD supports collaboration by allowing multiple team members to work on the same project simultaneously. Use the “Team Design” feature to share and synchronize design files.

1. Set Up Team Design: In the Project Manager, click on “File” > “Team Design” to set up team design. Assign roles and permissions to team members.
2. Synchronize Changes: Use the “Synchronize” tool to update and merge changes made by different team members.

Conclusion

OrCAD is a powerful and versatile tool for designing PCBs, offering a comprehensive suite of features for schematic capture, PCB layout, and simulation. By following this tutorial, you can learn how to create a schematic, design a PCB layout, and generate manufacturing files using OrCAD. Whether you’re a beginner or an experienced professional, OrCAD provides the tools and capabilities you need to bring your PCB designs to life.

As you continue to work with OrCAD, you’ll discover advanced features and techniques that can further enhance your design process. By leveraging these features and following best practices, you can create high-quality PCB designs that meet the demands of modern electronics. Whether you’re designing a simple prototype or a complex multi-layer board, OrCAD is a valuable tool that can help you achieve your design goals.