Panel Guidelines – PCBs Delivered in a Panel

Introduction to PCB Panels

Printed Circuit Boards (PCBs) are the backbone of modern electronics. They provide a platform for mounting and interconnecting electronic components, enabling the creation of complex electronic devices. In the manufacturing process, PCBs are often produced in panels, which are larger boards containing multiple identical PCB designs. This approach offers several advantages, including increased production efficiency, reduced costs, and improved quality control.

What is a PCB Panel?

A PCB panel, also known as a PCB array or PCB matrix, is a large board that contains multiple identical PCB designs arranged in a grid pattern. The individual PCBs are connected to the panel by small tabs called “mousebites” or “breakaway tabs.” Once the manufacturing process is complete, the individual PCBs are separated from the panel by breaking these tabs.

Advantages of Using PCB Panels

Increased Production Efficiency: Producing PCBs in panels allows for faster manufacturing times, as multiple boards can be processed simultaneously. This reduces setup times and minimizes the need for manual handling.
Reduced Costs: Panel-based production leads to lower material and labor costs, as less time and resources are required to produce the same number of PCBs compared to individual board production.
Improved Quality Control: When PCBs are manufactured in panels, it is easier to maintain consistent quality across all boards. Any issues or defects are likely to affect the entire panel, making them easier to identify and address.

Request RF PCB Manufacturing & Assembly Quote Now

PCB Panel Design Considerations

When designing PCBs for panel-based production, several factors must be considered to ensure optimal results.

Panel Size and Layout

The size and layout of the PCB panel depend on various factors, such as the size of the individual PCBs, the number of PCBs per panel, and the manufacturing capabilities of the PCB fabricator. Common panel sizes include:

Panel Size	Dimensions (mm)
18″ x 24″	457 x 610
21″ x 24″	533 x 610
18″ x 21″	457 x 533
16″ x 18″	406 x 457

When designing the panel layout, it is essential to consider the spacing between individual PCBs, as well as the placement of fiducial markers and tooling holes. Fiducial markers help align the panel during the manufacturing process, while tooling holes are used to secure the panel during drilling and routing operations.

Mousebites and V-Scoring

Mousebites, also known as breakaway tabs, are small tabs that connect the individual PCBs to the panel. They are designed to be easily broken, allowing the PCBs to be separated from the panel after manufacturing. The size and placement of mousebites should be carefully considered to ensure that they provide sufficient support during manufacturing while still being easy to break without damaging the PCBs.

V-scoring is an alternative method for separating PCBs from the panel. In this approach, a V-shaped groove is cut along the edges of the individual PCBs, making them easier to snap apart. V-scoring can provide a cleaner edge compared to mousebites, but it may not be suitable for all PCB designs.

Panelization Software

Panelization software tools help PCB designers create efficient panel layouts by automating the placement of PCBs, mousebites, and other panel features. Some popular panelization software options include:

PCB Panelizer by Numerical Innovations
GerberPanelizer by SoftwareForPCB
CAM350 by DownStream Technologies

These tools can significantly reduce the time and effort required to create optimized panel layouts, ensuring that the PCBs are produced efficiently and with minimal waste.

PCB Fabrication Process for Panels

The PCB fabrication process for panels is similar to that of individual PCBs, with a few additional steps to account for the panel-specific features.

Material Selection

The choice of PCB substrate material depends on the specific requirements of the PCB design, such as the desired electrical properties, thermal stability, and mechanical strength. Common PCB Substrate Materials include:

FR-4: A glass-reinforced epoxy laminate, widely used for general-purpose PCBs.
Rogers: High-frequency laminates with excellent dielectric properties, suitable for RF and microwave applications.
Aluminum: Metal-Core PCBs that offer superior thermal dissipation for high-power applications.

Copper Deposition and Patterning

The PCB fabrication process begins with the deposition of a thin layer of copper onto the substrate material. This copper layer is then patterned using a photolithographic process to create the desired circuit traces and pads.

Photoresist Application: A light-sensitive polymer, called photoresist, is applied to the copper surface.
Exposure: The photoresist is exposed to UV light through a photomask, which contains the circuit pattern.
Development: The exposed photoresist is removed, leaving behind a protective pattern on the copper surface.
Etching: The unprotected copper is etched away using a chemical solution, leaving behind the desired circuit pattern.
Photoresist Removal: The remaining photoresist is stripped away, revealing the patterned copper layer.

Lamination and Drilling

For multi-layer PCBs, the patterned copper layers are laminated together using heat and pressure, with insulating layers in between. Once the lamination process is complete, holes are drilled through the panel to create vias and component mounting holes.

Surface Finishing

To protect the copper traces and pads from oxidation and improve solderability, a surface finish is applied to the PCB panel. Common surface finishes include:

HASL (Hot Air Solder Leveling): A tin-lead alloy is applied to the copper surfaces using a hot air process.
ENIG (Electroless Nickel Immersion Gold): A thin layer of gold is deposited over a nickel barrier layer, providing excellent corrosion resistance and solderability.
OSP (Organic Solderability Preservative): A thin, organic coating is applied to the copper surfaces to prevent oxidation.

Solder Mask and Silkscreen

A solder mask, typically green in color, is applied to the PCB panel to protect the copper traces and prevent solder bridging during assembly. Openings in the solder mask are created to expose the pads for component placement.

A silkscreen layer is then applied to the panel, which contains text, logos, and component outlines to aid in the assembly process.

Electrical Testing

Before the individual PCBs are separated from the panel, electrical testing is performed to ensure that the boards function as intended. This testing can include:

Continuity Testing: Verifying that the desired electrical connections are present and that there are no short circuits.
Insulation Resistance Testing: Measuring the resistance between isolated conductors to ensure adequate insulation.
Functional Testing: Powering up the PCBs and testing their functionality using test fixtures or automated test equipment.

Depanelization

Once the PCB panel has passed electrical testing, the individual PCBs are separated from the panel. This process, called depanelization, can be accomplished using various methods, such as:

Manual Break: For panels with mousebites, the individual PCBs can be manually snapped out of the panel.
Routing: A CNC router can be used to cut the individual PCBs from the panel, following the pre-defined breakaway tabs or V-score lines.
Punching: A die-cutting machine can be used to punch out the individual PCBs from the panel.

After depanelization, the individual PCBs are ready for component assembly and final testing.

Best Practices for PCB Panel Design

To ensure the best results when designing PCBs for panel-based production, consider the following best practices:

Consult with Your PCB Fabricator: Engage with your PCB fabricator early in the design process to discuss their specific panel requirements, such as panel size, spacing, and breakaway tab design.
Optimize Panel Utilization: Arrange the PCBs on the panel to maximize the number of boards per panel while maintaining adequate spacing and support.
Use Standardized Panel Sizes: When possible, design your PCBs to fit within standard panel sizes to reduce production costs and lead times.
Incorporate Fiducial Markers: Include fiducial markers on your PCB panel to ensure accurate alignment during the manufacturing process.
Consider Depanelization Method: Design your breakaway tabs or V-score lines based on the intended depanelization method to minimize the risk of PCB damage.
Perform Design Rule Checks (DRC): Use PCB design software to perform DRC on your panel layout, ensuring that your design meets the fabricator’s specifications and industry standards.

Frequently Asked Questions (FAQ)

What is the difference between a PCB panel and an individual PCB?
A PCB panel is a larger board containing multiple identical PCB designs, while an individual PCB is a single, standalone board. PCB panels are used to increase production efficiency and reduce manufacturing costs.
What are mousebites, and why are they used in PCB panels?
Mousebites, also known as breakaway tabs, are small tabs that connect the individual PCBs to the panel. They provide support during the manufacturing process and allow the PCBs to be easily separated from the panel after production.
What are the advantages of using V-scoring instead of mousebites?
V-scoring can provide a cleaner edge when separating the PCBs from the panel compared to mousebites. However, V-scoring may not be suitable for all PCB designs and can be more expensive to implement.
How do I choose the right surface finish for my PCB panel?
The choice of surface finish depends on factors such as the desired solderability, corrosion resistance, and cost. Common surface finishes include HASL, ENIG, and OSP. Consult with your PCB fabricator to determine the best option for your specific application.
Can I mix different PCB designs on the same panel?
While it is possible to mix different PCB designs on the same panel, it is generally not recommended. Mixing designs can lead to increased complexity, higher production costs, and potential quality issues. It is best to use separate panels for each unique PCB design.

Conclusion

PCB panels play a crucial role in the efficient and cost-effective production of printed circuit boards. By understanding the design considerations, fabrication process, and best practices associated with panel-based PCB production, designers and manufacturers can ensure that their PCBs are produced to the highest quality standards while minimizing costs and lead times. Effective communication between PCB designers and fabricators is essential for optimizing panel layouts and achieving the best possible results.

As the demand for electronic devices continues to grow, the use of PCB panels will remain an essential aspect of PCB manufacturing. By staying up-to-date with the latest technologies and best practices in PCB panel design and production, manufacturers can stay competitive in an ever-evolving industry.