Introduction to Protel Autotrax for PCB Design

Protel Autotrax is a powerful software tool for designing printed circuit boards (PCBs). It provides a comprehensive set of features for schematic capture, PCB layout, routing, and manufacturing outputs. Whether you are a hobbyist or professional engineer, Protel Autotrax streamlines the PCB design process from concept to production.

In this article, we will walk through the steps of creating a PCB using Protel Autotrax. We’ll cover:

• Setting up a project
• Creating the schematic
• Defining the PCB stackup and design rules
• Placing components
• Routing the board
• Generating manufacturing files

By the end, you’ll have the knowledge to design your own custom PCBs in Protel Autotrax. Let’s get started!

Setting Up a New Protel Project

Create Project Folder

The first step is to create a new project folder to organize your design files:

1. Open Protel Autotrax
2. Go to File > New > Project
3. Choose a location and enter a name for the project folder
4. Click OK to create the project

Protel will create a new folder containing files for the schematic, PCB, outputs, and libraries.

Configure Project Options

Next, set up the project options to match your design requirements:

1. Go to Project > Project Options
2. Set units, grids, and other defaults
3. Define schematic and PCB file names
4. Click OK to apply settings

Take time to familiarize yourself with the various project options. You can always modify these later as needed.

Creating the Schematic

Place Components

Now you’re ready to start capturing the schematic:

1. Double-click the schematic file in the Projects panel to open it
2. Open the Libraries panel and browse for components
3. Drag-and-drop components from the library onto the schematic sheet
4. Repeat until all components are placed

Protel includes extensive part libraries. You can also create custom schematic symbols if needed.

Make Connections

Use wires and net labels to make connections between component pins:

1. Select Place > Wire from the menus
2. Click to start a wire, then click on a component pin
3. Continue clicking to route the wire, ending on another pin
4. To rename a net, select Place > Net Label, then attach the label to a wire

Wires and labels define the logical connectivity that will guide PCB layout and routing.

Add Power and Ground

Connect power and ground symbols to the appropriate component pins:

1. Select Place > Power Port or Ground
2. Click to place the power/ground symbol
3. Wire it to the associated component power/ground pins

Dedicated power and ground nets are important for proper PCB operation.

Annotate and Check

Prepare the schematic for the PCB layout phase:

1. Select Tools > Annotate to assign unique designators
2. Select Tools > Electrical Rules Check to verify the schematic
3. Resolve any warnings or errors

Annotation ensures that each component has a unique identifier. The ERC identifies common mistakes like unconnected pins or shorted outputs.

Defining the PCB Stackup

Set Layer Stack

Configure the layer stackup according to your PCB manufacturer specs:

1. Switch to the PCB file
2. Go to Design > Layer Stack Manager
3. Specify number of layers, copper weights, dielectrics, and thicknesses
4. Click OK to apply the stackup

The layer stack defines the physical structure of the board. Work with your manufacturer to determine the optimal stackup.

Assign Net Classes

Use net classes to group nets with similar routing requirements:

1. Go to Design > Net Classes
2. Click Add to create a new net class
3. Specify width, clearance, via sizes and other constraints
4. Click OK and repeat for additional net classes

Typical net classes include signal, power, and high-speed. Consult your manufacturer for recommended geometries.

Transferring from Schematic to PCB

Update PCB from Schematic

To synchronize the schematic and PCB:

1. Switch to the PCB file
2. Select Design > Update PCB from Schematic
3. Choose “Execute Changes” and click OK

This imports the netlist from the schematic to the PCB, adding components and connections.

Component Placement

Arrange components on the board for optimal routing and manufacturability:

1. Select Edit > Component Placement > Manually
2. Click and drag components to desired locations
3. Use the Align tools to line up components
4. Rotate and flip components as needed

Group associated components together. Aim for short, direct connections. Place connectors near board edges.

Fanning Out

Fan out surface mount pads for easier routing:

1. Select Edit > Component Placement > Fan Out
2. Choose desired via and trace sizes
3. Select components and click OK

Fanning out typically uses blind/buried vias to access inner signal layers. This is essential for high pin-count parts.

Routing the PCB

Manual Routing

Route critical or complex nets by hand:

1. Select Route > Interactive Routing
2. Click to start a trace, then click to add vertices
3. Press Shift+R to cycle through layers while routing
4. Double-click or press Enter to finish the trace

Manual routing offers the most control. Use it for sensitive analog nets, differential pairs, or dense BGA breakouts.

Autorouting

Let Protel route the remaining nets automatically:

1. Select Route > Situs Autorouter
2. Adjust settings if desired
3. Click Route to begin autorouting
4. Review the results and re-route if needed

The autorouter can quickly complete the less critical routes. However, always double-check its work.

Tuning Constraints

Modify design rules to fine-tune routing:

1. Go to Design > Rules
2. Select a rule category such as Routing or SMT
3. Adjust clearances, widths, via styles, etc.
4. Click OK to apply changes

Stricter constraints help ensure manufacturability but may make routing more difficult. Aim for a balance.

Manufacturing Output Generation

Create Gerber Files

Export Gerber files for PCB fabrication:

1. Go to File > Fabrication Outputs > Gerber Files
2. Set up layer mapping and file naming
3. Click OK to generate Gerbers

Gerber is the standard format for PCB manufacturing data. Review the generated files before submitting.

Generate Drill Files

Export NC drill files for drilling and routing:

1. Go to File > Fabrication Outputs > NC Drill Files
2. Specify drill units, file format, and naming
3. Click OK to generate drill files

The NC drill files tell the manufacturer where to drill holes and route board outlines.

Create Assembly Drawings

Generate assembly drawings to aid in PCB assembly:

1. Go to File > Assembly Outputs > Assembly Drawings
2. Choose which layers and markings to include
3. Click OK to create the drawings

Assembly drawings show component locations and reference designators. They help the assembler orient and place parts correctly.

Output Pick and Place

Export pick and place files for automated assembly:

1. Go to File > Assembly Outputs > Pick and Place Files
2. Select output units and file format
3. Click OK to generate the files

Pick and place data specifies the centroid and rotation of each component. It is used to program the assembly machine.

Conclusion

Protel Autotrax provides a robust environment for designing and documenting PCBs. By following the steps outlined above, you can efficiently create a complete PCB design package ready for manufacture.

Remember to:

• Set up projects with clear folder structures and naming conventions
• Capture the full schematic, including power, ground, and net names
• Define an appropriate layer stack and net classes for your application
• Place and route components mindfully, balancing density and manufacturability
• Generate a comprehensive set of manufacturing and assembly files

With practice, you’ll develop your own design style and techniques within the Protel Autotrax framework. Don’t hesitate to consult the documentation, online forums, or local experts for guidance.

Happy PCB designing!

FAQ

What is the best way to learn Protel Autotrax?

The best way to learn Protel Autotrax is a combination of methods:

1. Work through the built-in tutorials and documentation
2. Study and recreate existing designs
3. Take on simple projects to build hands-on experience
4. Participate in online forums and user groups to learn from others

Consistent practice is key. Start with basic designs and gradually take on more complex challenges.

How do I create custom component footprints?

To create a custom component footprint in Protel:

1. Open the PCB Footprint Library Editor
2. Select File > New > Footprint
3. Set up the footprint properties like name, designator, and description
4. Use the drawing tools to create pads, shapes, and silkscreens
5. Specify the component courtyard and assembly/manufacturing settings
6. Save the footprint in a library

It’s important to follow IPC standards and match the manufacturer’s recommended land patterns.

What is the difference between Gerber and ODB++ outputs?

Gerber and ODB++ are both PCB manufacturing output formats, but they differ in structure and capabilities:

Format	Structure	Capabilities
Gerber	Set of individual files for each layer	Basic copper, drill, and fill data
ODB++	Single unified database with all layers	Adds nets, components, and testing

ODB++ offers more intelligent data exchange but requires compatible CAD and CAM tools. Gerber remains the most widely accepted standard.

How do I optimize my PCB for high-speed signals?

To optimize a PCB for high-speed signals:

1. Use a controlled-impedance stackup with dedicated signal and plane layers
2. Route critical traces as matched-length differential pairs
3. Provide solid reference planes adjacent to signal layers
4. Add stitching vias to connect reference planes
5. Minimize stubs and unterminated traces
6. Apply shielding and filtering where necessary

At multi-gigabit speeds, it’s crucial to simulate and validate the PCB layout before manufacturing.

What are some common PCB design mistakes to avoid?

Some common PCB design mistakes include:

1. Incomplete or inconsistent schematic capture
2. Inadequate layer stackup or reference planes
3. Incorrect footprints or pinouts
4. Mismatched differential pairs
5. Insufficient clearances or creepage distances
6. Misaligned drill and outline data

Fortunately, most of these mistakes are preventable with proper planning, rule definitions, and design reviews. When in doubt, consult the manufacturer early to avoid costly re-spins.