Panelization is a process in PCB manufacturing where multiple printed circuit boards (PCBs) are grouped together on a single panel for production. This technique is commonly used to increase manufacturing efficiency, reduce costs, and simplify the assembly process. Panelization allows for the simultaneous fabrication of multiple PCBs, which are later separated into individual boards using Breakaway Tabs or mouse bites.
When designing panels for PCB manufacturing, it is crucial to consider the appropriate dimensions to ensure proper fabrication and assembly. The following factors should be taken into account when determining panelization dimensions:
Panel Size
The panel size is the overall dimension of the panel, including all the individual PCBs and the spacing between them. Common panel sizes include:
Panel Size
Dimensions (mm)
Small
100 x 100
Medium
200 x 200
Large
300 x 300
Extra Large
400 x 400
The choice of panel size depends on the dimensions of the individual PCBs, the number of boards to be panelized, and the manufacturing capabilities of the PCB fabricator.
PCB Spacing
PCB spacing refers to the distance between the individual PCBs on the panel. Adequate spacing is necessary to ensure proper separation of the boards and to avoid any interference during the assembly process. The recommended PCB spacing depends on the size of the individual boards and the panelization method used.
PCB Size
Recommended Spacing (mm)
Small
2 – 3
Medium
3 – 4
Large
4 – 5
Extra Large
5 – 6
Breakaway Tabs
Breakaway tabs, also known as breakaway rails or snap-off tabs, are small tabs that connect the individual PCBs to the panel frame. These tabs allow for easy separation of the boards after the manufacturing process is complete. The dimensions of the breakaway tabs are critical to ensure clean and efficient separation without damaging the PCBs.
Tab Parameter
Recommended Dimension (mm)
Width
2 – 3
Length
5 – 10
Thickness
0.8 – 1.2
The number and placement of breakaway tabs depend on the size and shape of the individual PCBs. Generally, smaller PCBs require fewer tabs, while larger boards may need additional tabs for secure attachment to the panel frame.
Mouse Bites
Mouse bites, also known as perforations or V-grooves, are small, V-shaped cuts made along the edges of the individual PCBs. These cuts create a weak point, allowing for easy separation of the boards from the panel. The dimensions of the mouse bites are important to ensure clean breakage without leaving excessive material on the board edges.
Mouse Bite Parameter
Recommended Dimension (mm)
Depth
0.3 – 0.5
Width
0.8 – 1.2
Pitch
1.5 – 2.5
The depth of the mouse bites should be approximately 1/3 to 1/2 of the PCB Thickness to ensure easy separation without compromising the structural integrity of the board during manufacturing.
When designing panels for PCB manufacturing, several key considerations should be kept in mind to ensure optimal results:
Board Orientation
The orientation of the individual PCBs on the panel can impact the manufacturing process and the overall efficiency. Consider the following factors when determining board orientation:
Minimizing the panel area to reduce material waste
Aligning the boards for easy assembly and soldering
Ensuring proper placement of breakaway tabs and mouse bites
Fiducial Marks
Fiducial marks are small, circular, or cross-shaped marks placed on the panel to serve as reference points for automated assembly equipment. These marks help align the panel accurately during the pick-and-place process and ensure precise component placement. When designing panels, include fiducial marks in the following locations:
Panel corners: Place fiducial marks near the corners of the panel for global alignment.
Individual PCBs: Include fiducial marks on each PCB for local alignment during assembly.
Tooling Holes
Tooling holes are small holes drilled in the panel frame that serve as reference points for the manufacturing equipment. These holes help secure the panel during the fabrication process and ensure accurate alignment. When designing panels, consider the following guidelines for tooling holes:
Size: Tooling holes typically have a diameter of 2.4 mm to 3.2 mm.
Location: Place tooling holes near the corners of the panel, ensuring they do not interfere with the individual PCBs or breakaway tabs.
Copper Balance
Copper balance refers to the even distribution of copper on both sides of the PCB to prevent warping during the manufacturing process. When panelizing PCBs, ensure that the copper distribution is balanced across the entire panel to minimize the risk of warping and ensure consistent fabrication results.
Panelization Methods
There are several panelization methods available, each with its own advantages and considerations:
Rigid Panels
Rigid panels are the most common panelization method, where individual PCBs are arranged on a single, solid panel. This method is suitable for most PCB Designs and offers good structural stability during manufacturing.
Flexible Panels
Flexible panels, also known as matrix panels, are used for PCBs with irregular shapes or sizes that cannot be efficiently panelized using rigid panels. In this method, the individual PCBs are connected using thin, flexible tabs that allow for easy separation after manufacturing.
Step-and-Repeat Panelization
Step-and-repeat panelization is a technique where a single PCB design is repeated multiple times on a panel, creating an array of identical boards. This method is useful for high-volume production runs and helps minimize tooling costs.
Mixed Panels
Mixed panels, also known as multi-circuit panels, involve the panelization of different PCB designs on a single panel. This method is useful when producing small batches of various PCB designs, as it helps reduce tooling costs and setup times.
FAQ
1. What is the minimum spacing between PCBs on a panel?
The minimum spacing between PCBs on a panel depends on the size of the individual boards and the panelization method used. Generally, a spacing of 2 mm to 3 mm is recommended for small PCBs, while larger boards may require a spacing of 4 mm to 6 mm.
2. Can I panelize PCBs with different thicknesses on the same panel?
Yes, it is possible to panelize PCBs with different thicknesses on the same panel. However, this may require special considerations during the manufacturing process, such as adjusting the depth of the mouse bites or using different tooling for each thickness. Consult with your PCB Manufacturer to determine the feasibility and any additional requirements for panelizing PCBs with varying thicknesses.
3. What is the recommended width for breakaway tabs?
The recommended width for breakaway tabs is typically between 2 mm and 3 mm. This width provides sufficient strength to hold the individual PCBs securely during manufacturing while allowing for easy separation after the process is complete.
4. How do I determine the number and placement of fiducial marks on a panel?
The number and placement of fiducial marks on a panel depend on the size of the panel and the individual PCBs. As a general guideline, place fiducial marks near the corners of the panel for global alignment and on each individual PCB for local alignment during assembly. Consult with your PCB manufacturer for specific recommendations based on your panel design.
5. Can I panelize PCBs with different copper weights on the same panel?
Yes, it is possible to panelize PCBs with different copper weights on the same panel. However, this may require additional considerations during the manufacturing process to ensure proper copper balance and prevent warping. Discuss your specific requirements with your PCB manufacturer to determine the feasibility and any necessary adjustments for panelizing PCBs with varying copper weights.
Conclusion
Panelization is an essential aspect of PCB manufacturing that helps increase efficiency, reduce costs, and simplify the assembly process. When designing panels for PCB production, it is crucial to consider the appropriate dimensions for panel size, PCB spacing, breakaway tabs, and mouse bites. Additionally, factors such as board orientation, fiducial marks, tooling holes, and copper balance should be taken into account to ensure optimal results.
By understanding the various panelization methods and their associated considerations, designers and manufacturers can create panels that meet their specific requirements while ensuring high-quality, reliable PCBs. Effective communication between the design team and the PCB manufacturer is essential to address any unique challenges and find the best panelization solution for each project.
As PCB technology continues to evolve, the importance of proper panelization remains paramount. By staying informed about the latest techniques and guidelines, designers and manufacturers can optimize their panelization processes, leading to improved efficiency, reduced waste, and higher-quality end products.
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