How to Panelise Round Shaped PCB’s

EMS - 24 July 2024 - 12:34 am

What is PCB Panelization?

PCB Panelization is the process of grouping multiple printed circuit board designs onto a single panel for manufacturing. Panelizing PCBs provides several benefits:

Reduced manufacturing costs by producing multiple PCBs in one production run
Improved handling and assembly of smaller PCBs
Optimized material usage and minimized waste
Increased throughput and efficiency in the assembly process

When dealing with unusually shaped PCBs, such as round boards, panelization becomes more challenging but is still an important optimization in the manufacturing process.

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Challenges of Panelizing Round PCBs

Round shaped PCBs present unique challenges for panelization compared to standard rectangular boards:

Challenge	Description
Inefficient material usage	Circular boards do not tessellate, leading to unused material between boards
Reduced panel strength	Circular cut-outs weaken the overall panel structure
Specialized depaneling	Round boards require unique depaneling methods like perforations or mouse bites

Despite these challenges, there are several techniques that can be employed to effectively panelize round PCBs.

Techniques for Panelizing Round PCBs

1. Tessellation

One approach to panelizing round PCBs is to tessellate them in a hexagonal pattern. This minimizes the unused material between boards compared to a square grid arrangement.

Advantages:
– Improved material utilization
– Uniform spacing between boards

Disadvantages:
– More complex panel design
– Hexagonal panels are less common and may incur higher costs

2. Sub-panels

Grouping round PCBs into rectangular sub-panels can simplify the overall panel design. Each sub-panel contains a small number of boards (e.g., 2-4) which are then arranged into a larger rectangular panel.

Advantages:
– Rectangular sub-panels are easier to work with
– Allows for mixed board shapes and sizes in a single panel

Disadvantages:
– Sub-panels add complexity to the panelization process
– May not achieve optimal material utilization

3. Perimeter Tabs

Adding tabs around the perimeter of each round PCB allows them to be panelized in a rectangular array while still being easily depaneled after assembly.

Advantages:
– Simple rectangular panel design
– Boards can be depaneled by breaking the perimeter tabs

Disadvantages:
– Perimeter tabs add to the overall board size
– Depaneling leaves visible tab stubs on the board edge

Depaneling Techniques for Round PCBs

Depaneling is the process of separating individual boards from the panel after assembly. Specific depaneling techniques are needed for round boards to ensure clean, smooth edges without damaging the components.

V-Scoring

V-scoring uses a V-shaped blade to cut partway through the panel, creating a weak point where the boards can be easily snapped apart by hand.

Advantages:
– Creates a clean, smooth edge
– Minimal stress on the board during depaneling
– Suitable for both prototypes and production

Disadvantages:
– Requires specialized V-scoring equipment
– Limited to straight-line board edges
– May leave visible score marks

Mouse Bites

Mouse bites are small, closely spaced drill holes that perforate the board perimeter, allowing the panel to be easily broken apart.

Advantages:
– No specialized equipment needed
– Suitable for curved or irregular board shapes
– Cost-effective for prototype and low-volume production

Disadvantages:
– Leaves rough, uneven board edges that may require secondary finishing
– Drill holes may impact edge components or traces
– Not suitable for high-volume production

Routing

Routing uses a CNC mill to cut the individual boards out of the panel.

Advantages:
– Creates smooth, finished board edges
– Precise control over board shape and outline
– Suitable for high-volume production

Disadvantages:
– Requires specialized CNC routing equipment
– More expensive than other depaneling methods
– Milling can cause stress on the board and components

Best Practices for Panelizing Round PCBs

Consider the panelization strategy early in the design process. Board shape, size, and component placement can impact the panelization options.
Choose a panelization technique that balances material utilization and manufacturing efficiency. Hexagonal tessellation offers the best material usage, but rectangular panels with sub-panels or perimeter tabs may be more practical.
Design with depaneling in mind. Select a depaneling method appropriate for the board shape, components, and production volume. Add necessary features like v-score lines or mouse bite perforations.
Communicate clearly with your manufacturer. Provide detailed panel drawings and specifications to ensure the boards are fabricated and depaneled correctly.
Test and validate the panelization design. Produce a small batch of panels to verify the design, assembly, and depaneling process before committing to full production.

FAQ

1. What is the minimum spacing between round boards in a panel?

The minimum spacing between boards depends on the panelization technique and the specific manufacturer’s requirements. Generally, a spacing of at least 2-3mm is recommended to maintain panel strength and allow for clean depaneling.

2. Can mixed board shapes be panelized together?

Yes, mixed board shapes can be panelized together using sub-panels. Each sub-panel can contain a group of identical boards, which are then arranged into a larger panel. This allows for different board shapes and sizes to be manufactured in a single panel.

3. What is the maximum panel size for round PCBs?

The maximum panel size depends on the manufacturer’s equipment and capabilities. Common panel sizes range from 18×24 inches (457x610mm) to 21×24 inches (533x610mm), but larger sizes may be available. Consult with your manufacturer to determine the maximum panel size for your specific project.

4. How does panelization affect the cost of round PCBs?

Panelization can significantly reduce the cost of manufacturing round PCBs by allowing multiple boards to be produced in a single run. The cost savings depend on the panel design, board complexity, and production volume. In general, larger panels with more boards will result in lower per-board costs.

5. Can components be placed near the edge of a round PCB?

Yes, components can be placed near the edge of a round PCB, but proper design considerations must be made. Adequate clearance should be provided between the components and the board edge to avoid interference with depaneling. Additionally, any perimeter tabs or mouse bites should be positioned to avoid components and critical traces.

Conclusion

Panelizing round PCBs presents unique challenges compared to traditional rectangular boards, but with proper planning and execution, it can significantly optimize the manufacturing process. By understanding the various panelization and depaneling techniques, designers can create efficient panel layouts that minimize material waste, reduce costs, and improve production throughput. Effective communication with the manufacturer and thorough testing are essential to ensure a successful outcome. By following best practices and considering panelization early in the design process, round PCBs can be efficiently and cost-effectively manufactured in panel form.

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