PCB Panelization Techniques: A Complete Guide

Different PCB panelization techniques achieve varying results. Some suit specific PCB types, while some are best for particular materials. This article aims to introduce you to these panelization methods, their features, and how to choose the best option.

What is PCB Panelization

PCB panelization means grouping multiple printed circuit boards into one large piece. The PCBs later undergo separation either manually or mechanically. Laser cutting is also a popular depanelization method.

The individual boards may have similar designs or different ones. Sizes also vary depending on the manufacturer’s equipment. Standard panel sizes include 18 x 24 or 21 x 24 inches. Larger or smaller panels are also possible.

On the other hand, a single panel may hold from a few to hundreds of individual PCBs. It depends on the panel size and that of the panelized PCBs. It also depends on the panelization method used.

For example, an 18 by 24 inch panel may hold 42 PCBs measuring 2 inches by 4 inches. What matters most is the panel size that the manufacturer can handle. The ability varies across different vendors.  

Why is Panelization Important?

Many PCB manufacturing systems do not support individual PCBs, especially if the boards are too small. Assembly machines often require specific sizes for manufacturability and other purposes. Having multiple boards in a panel offers these benefits.

• Cost-Effective Manufacturing: It allows the manufacturer to reduce manufacturing expenses, resulting in lower per PCB costs.
• Material Savings: There’s less wastage of PCB materials when you combine several pieces into one board.
• Enhanced Efficiency: Panelization streamlines board fabrication processes, making PCB production more efficient than when handling single boards.
• Assembly Benefit: It ensures uniformity, especially during component placement by pick-and-place machines and when soldering.

PCB Panelization Techniques

PCB panelization methods include V-scoring, tab routing, and breakaway rails. It can also be custom cut-outs that match specific requirements, such as circuit board and material type.

V-Scoring

This method involves cutting V-shaped grooves into the board using a CNC router. The cuts reduce thickness, creating lines of weakness. The grooves are usually 30° or 45°. Snapping the board along the lines separates the PCBs.

V-grooves are easy to make and cost-effective. However, they are less suitable for delicate PCBs or those with edge components. You cannot effectively use it on irregularly shaped boards, which limits its application.

Tab Routing

Tab routing is a technique where a router produces small tabs between the PCBs on the panel. The tabs present easy separations, usually by breaking them.

The technique is an ideal choice for smaller and delicate boards. It also suits those that feature near-edge parts and other complex features. The only downside is that they cost more to create.

Perforated Tabs

Often referred to in the industry as ‘Mouse Bites’, these are tabs with small perforations made to separate individual PCBs. They are a good choice when handling PCBs with edge components since they reduce damage.

The perforations also suit smaller circuit boards with limited space for separation features. They also produce clean cuts. However, they are costly to make.

Breakaway Rails

Breakaway rails are solid extensions added to provide mechanical support. They are usually necessary when the individual boards are too small or irregularly shaped.

The rails are typically used in combination with V-grooves or other panelization features. Their drawback is that they increase material usage and add extra steps to the fabrication process.

Custom Cut-outs

These are unique openings designed to accommodate specific features, such as component positions, board shapes, and other needs. The designer introduces them early on, preparing the panel for the manufacturing process.

How to Choose a PCB Panelization Method

Each panelization method has an application that it suits best. The following are key PCB panelization guidelines and considerations when selecting a technique to use.

Board Size and Shape

V-grooving is best for rectangular PCBs (both large and small) to minimize material waste, as it requires no gap between boards. Tab routing is necessary for irregular shapes (circles, L-shapes).

Component Placement

The location of board components significantly influences your panelization choices. For instance, some techniques may not suit components that are too close to the edges and vice versa.

Edge Quality Needs

V-scoring produces a straight edge, while perforated tabs (mouse bites) leave small rough bumps. Depending on the project’s housing requirements, choose what best suits your needs.

Production Volume

Some panelization methods do not support fast production. They may take time to create or need special care and equipment to separate. Your choice should not make panelization and breaking challenging.

PCB Panel Design Considerations

Various design factors impact the panelization of PCB boards. Designers must employ best practices when incorporating the features. The factors to consider when designing the panel include:

Panel Borders

Borders are critical when designing panels. It’s standard practice to ensure over 5 mm clearance all around the board. That’s in addition to providing sufficient distance between the PCBs or components and breakaway lines.

Fiducial Marks

Fiducial markers guide automated manufacturing equipment, making their size and correct placement critical. They typically range from 1.0 mm to 3.0 mm in diameter (with a larger clearance mask).

Their distance from the edge of the panel is usually specific to the machine requirements. The clearance ensures their visibility as the panel moves through the fabrication and assembly line.

Tooling Holes

Tooling holes help manufacturing equipment to hold the panel in place during various procedures, such as drilling. Designers must correctly position the holes when creating panelization features.

Breakaway Strength

The designer ensures a balance between panel strength and the amount of force required to separate the PCBs safely. The separation lines should not be too weak to interfere with manufacturing or too strong for breakage.

Conclusion

Various PCB panelization techniques are available for use. Understanding them is helpful when designing your PCB. Your manufacturer may also request that you choose a preferred method. It’s crucial that the method suits the board type, manufacturing constraints, and estimated costs.