What is Cross Probing?

Cross probing, also known as cross selecting or cross highlighting, is the ability to quickly locate a component on a PCB layout by selecting it in an associated BOM or schematic, or vice versa. When you cross probe a component, the corresponding component is automatically highlighted in all other related documents.

For example, let’s say you’re reviewing a densely populated PCB layout and need to find a specific 10K resistor based on its reference designator. Rather than hunting through the board to find the right component, you can simply locate the resistor in the BOM and cross probe it. The corresponding component will be instantly highlighted on the PCB layout, allowing you to quickly find it on the board.

Cross probing works bi-directionally. You can cross probe from a BOM to a PCB layout or schematic, from a PCB layout to a BOM or schematic, or from a schematic to a BOM or PCB layout. This allows you to quickly navigate between different design documents and ensures that changes in one document are automatically reflected in the others.

How Does Cross Probing Work?

Cross probing relies on the intelligent integration of PCB BOM management software with PCB design tools. The BOM software acts as a central hub that maps components in the BOM to their corresponding parts on the PCB layout and schematic.

Here’s a simplified overview of how cross probing works:

1. The PCB BOM software imports the BOM, PCB layout, and schematic files from the PCB design tool.
2. The BOM software analyzes the files and creates intelligent links between components in the BOM and their corresponding parts in the PCB layout and schematic.
3. When a user selects a component in the BOM, PCB, or schematic, the BOM software looks up the associated links and automatically highlights the corresponding parts in the other documents.

Modern PCB BOM tools support intelligent data mapping that can handle complex BOMs and design files from different EDA tools. They use sophisticated algorithms to match components based on reference designators, part numbers, values, and other key properties, even if there are discrepancies or missing information between the files.

Benefits of Cross Probing

Cross probing provides several important benefits for PCB designers:

1. Speeds Up Design Reviews

One of the biggest advantages of cross probing is that it allows you to quickly navigate complex PCB designs and locate specific components easily. This is especially valuable during design reviews, when you need to examine individual components and verify their placement and connections.

Without cross probing, reviewing a complex PCB can be a tedious and time-consuming process. You would need to search through the PCB layout to find each component, then cross-reference it with the schematic and BOM to verify it’s the correct part. Cross probing automates this process. You can simply click on a component in any document and instantly see where it is in the other files.

2. Catches Errors Early

Cross probing also helps you catch design errors early in the PCB design process, before they become costly mistakes. By providing an easy way to cross-reference components between design documents, cross probing makes it easy to spot inconsistencies and errors, such as:

• Incorrect component placements: Cross probing can help you verify that components are placed in the correct locations on the PCB by allowing you to quickly compare their placement with the schematic.
• Incorrect component values: Cross probing can help you check that the correct component values are used in the PCB layout by allowing you to easily compare values between the BOM and PCB.
• Missing components: Cross probing can help you identify components that are missing from the PCB layout by allowing you to quickly check if all the components in the BOM have corresponding parts on the board.

Catching these types of errors early can save significant time and money by avoiding the need for redesigns and respins later in the development process.

3. Facilitates Collaboration

Finally, cross probing facilitates collaboration between different members of the PCB design team. By providing a common reference point for components across different design documents, cross probing makes it easier for team members to communicate and collaborate effectively.

For example, a designer can use cross probing to quickly show a colleague where a specific component is located on the PCB layout, even if the colleague is working from the schematic or BOM. This can help avoid confusion and miscommunication, and ensure that everyone is on the same page.

Cross probing also facilitates collaboration between PCB designers and other stakeholders, such as procurement and manufacturing teams. By providing a clear and unambiguous link between the BOM and PCB, cross probing helps ensure that the right components are procured and used in the final assembly.

Best Practices for Cross Probing

To get the most out of cross probing, there are a few best practices to keep in mind:

1. Use a Dedicated PCB BOM Tool

While many PCB design tools include basic BOM management features, using a dedicated PCB BOM tool that supports cross probing can provide significant advantages. Dedicated BOM tools typically offer more advanced features for data mapping, data validation, and collaboration, which can streamline your design process and reduce errors.

Some of the key features to look for in a PCB BOM tool include:

• Support for intelligent data mapping and cross probing
• Integration with popular PCB design tools
• Automated BOM validation and error checking
• Collaborative features for sharing and reviewing BOMs with team members
• Reporting and analytics features for tracking component costs, lead times, and other key metrics

2. Keep Your BOM Up to Date

Cross probing is only effective if your BOM is accurate and up to date. Therefore, it’s important to maintain a disciplined approach to BOM management throughout the PCB design process.

Some tips for keeping your BOM up to date include:

• Updating the BOM regularly as components are added, removed, or changed in the design
• Using a consistent naming convention for components and reference designators across all design documents
• Performing regular BOM audits to catch errors and inconsistencies
• Leveraging automated BOM validation tools to check for common errors and data integrity issues

3. Use Cross Probing Early and Often

To get the most value from cross probing, it’s important to use it early and often throughout the PCB design process. Don’t wait until the end of the design cycle to start cross probing components. Instead, make cross probing a regular part of your design workflow from the beginning.

Here are some key points in the design process where cross probing can be particularly valuable:

• During schematic capture: Use cross probing to verify that components are correctly associated with their schematic symbols and to check for missing or incorrect connections.
• During PCB layout: Use cross probing to verify component placements, check for spacing and clearance issues, and ensure that all required components are placed on the board.
• During design reviews: Use cross probing to quickly navigate the design and check for errors or inconsistencies, and to facilitate communication between team members.
• During BOM finalization: Use cross probing to verify that the final BOM matches the PCB layout and schematic, and to check for any last-minute errors or discrepancies.

By using cross probing regularly throughout the design process, you can catch errors early, avoid unnecessary rework, and streamline your overall design workflow.

FAQ

What is the difference between cross probing and cross selecting?

Cross probing and cross selecting are essentially the same thing. Both terms refer to the ability to select a component in one design document (such as a BOM, schematic, or PCB layout) and have the corresponding component automatically highlighted in the other documents. The terms are often used interchangeably.

Can cross probing handle multi-channel designs?

Yes, modern PCB BOM tools that support cross probing can typically handle multi-channel designs with hierarchical schematics and multi-board assemblies. The key is to ensure that your BOM tool has the necessary features to support your specific design requirements, such as the ability to map components across multiple schematic pages or PCB files.

What happens if there are discrepancies between the BOM and PCB?

If there are discrepancies between the BOM and PCB, such as missing or incorrect components, the cross probing tool will typically flag the errors and provide visual indicators to help you identify and resolve the issues. Some tools may also provide automated error checking and validation features to help you catch discrepancies early in the design process.

Can cross probing be used with 3D PCB designs?

Yes, many modern PCB BOM tools support cross probing for 3D PCB designs. This allows you to select components in the BOM and see them highlighted in the 3D PCB model, which can be useful for visualizing component placements and checking for clearance issues. However, the specific capabilities and requirements for 3D cross probing may vary depending on the tools you are using.

How much time can cross probing save in the PCB design process?

The amount of time that cross probing can save in the PCB design process varies depending on the complexity of the design and the specific tools and workflows being used. However, many PCB designers report significant time savings by using cross probing, particularly in the later stages of the design process when errors and inconsistencies can be more costly to fix.

According to a survey by EMA Design Automation, PCB designers who use cross probing estimate that it saves them an average of 2-4 hours per design, with some reporting savings of up to 8 hours or more on complex designs. Over the course of a year, this can add up to significant time and cost savings for PCB design teams.

Conclusion

Cross probing is a powerful technique that can greatly streamline the PCB design process by providing a quick and easy way to locate and verify components across different design documents. By using a dedicated PCB BOM tool that supports cross probing, and following best practices for BOM management and design collaboration, PCB designers can catch errors early, avoid unnecessary rework, and ultimately bring their products to market faster and with higher quality.

As PCB designs continue to increase in complexity and time-to-market pressures continue to rise, cross probing and other advanced BOM management techniques will become increasingly essential tools for PCB design teams. By embracing these tools and best practices, designers can stay ahead of the curve and deliver better products, faster.

	Schematic Capture	PCB Layout	Design Review	BOM Finalization
Cross Probing Benefits	Verify component associations and connections	Verify component placements and clearances	Quickly navigate and check for errors	Verify final BOM matches PCB and schematic
Time Savings	1-2 hours	2-4 hours	2-3 hours	1-2 hours

Estimated time savings from using cross probing at different stages of PCB design process. Actual savings may vary depending on design complexity and specific tools used.