A flexible PCB array is like a big board made up of several flexible circuit boards. They’re usually made this way during production so they can be connected and produced in batches all at once. After the production is completed, they are separated by cutting or disconnecting. The benefit of a flexible PCB array is that it can improve production efficiency and save costs.
Flex PCB Array Layout Methods
The way you lay out a flex PCB panel is super important for manufacturing. It decides how to fit multiple flex PCBs on one panel to use space wisely and waste less material. There are various layout styles used for flex PCB panels, depending on the specific needs of the production process:
Positive Layout (Forward Layout)
In this layout, all the individual flex PCBs are lined up in the same direction, with the components and traces positioned in a way that allows the entire array to be processed in one go. This way is simple and efficient, making it the most common choice for mass production.
Negative Layout (Reverse Layout)
Unlike the positive layout, the negative layout involves arranging the PCBs in such a way that some of them are rotated or mirrored. This layout is typically used when there is a need to create different orientations for the final products or to optimize space utilization on the panel.
Tilted Layout (Angled Layout)
The tilted layout involves positioning the individual flex circuit boards at an angle, often 45 degrees or another specified angle. This arrangement allows for better space optimization, especially when the shape of the PCBs is non-standard or when components need to be positioned in a way that best fits the design.
Mixed Sizes Layout
In some cases, a flex PCB panel may include PCBs of varying sizes, arranged in a way that maximizes the use of available space. This mixed sizes layout is especially useful when different size flexible PCBs are needed for a particular application, as it allows for a combination of smaller and larger PCBs on a single panel.
Each of these layout methods is designed to balance the needs of space efficiency, production speed, and final product requirements, depending on the type of devices being produced and the scale of manufacturing.
Several key points when layout panels
Try to be compact: Minimize the distance between panels while ensuring smooth production, so that more products can be assembled on one panel, less material is used, and the cost is naturally reduced.
Keep a distance: Leave at least 2 mm of space between each panel to place the small holes used for positioning. In mass production, molds are usually used to punch holes, which is more accurate. When producing samples, laser cutting may be used to avoid problems with the entire panel due to a small deviation.
Make a mark: Add some etched characters such as the specifications of the panel, product number, etc. to the panel, which is convenient for subsequent inspection and production.
Positioning holes: Add positioning holes to the four corners of the panel, and select a corner to make a special mark, so that the direction can be guaranteed to be correct in the subsequent production process, and there will be no problems such as incorrect sealing position or crooked character printing due to the wrong direction.
The panel width is fixed at 250mm because the conventional size of copper foil is 250mm. The length is kept within 390mm as much as possible, which is usually limited by the depth of the plating tank. The larger the panel size, the greater the offset, the worse the production accuracy, and the higher the product failure rate.
How Are Circuits Separated in a Flex PCB Array?
The final step in the manufacturing process is separating the individual flex PCBs from the array. This is typically done in a process known as de-paneling, which involves several methods depending on the design and specific requirements of the production:
V-Cut (V-Scoring)
The V-Cut method, often used for rigid boards or rigid-flex circuit boards, involves scoring the panel along predetermined V-shaped lines, allowing the individual PCBs to be separated by bending the panel. This method is not typically used for flexible PCBs but is a common technique for PCB or rigid-flex PCB arrays, where the components and traces are less likely to be damaged by bending. The V-Cut is ideal for rigid PCBs and hybrid designs, offering a simple, cost-effective method for panel separation.
Stamp Hole
The stamping method, or postal hole method, involves punching small holes in the panel around the individual flex PCBs. The holes act as weak points that allow the PCBs to be separated easily without affecting the integrity of the flexible circuits. This method is particularly useful for high-speed production and when the array needs to be handled quickly.
Laser Cutting
Laser cutting can be used for flexible and rigid circuit boards with high precision. It's perfect for complex designs and ensures that the flexible circuits aren't damaged during separation. Laser cutting is accurate and efficient, so it's a great choice for removing flexible PCBs from a panel while keeping the design intact.
Punching
Punching is typically used to separate flexible PCBs from a panel, especially in mass production. However, this method is less efficient when used for rigid boards. The punching process involves a mechanical press that removes the individual circuits from the array. This method is fast and widely used in high-volume production.
Tab Routing
Tab routing is employed for arrays that include non-standard shapes or require special handling. In this process, small tabs are left to hold the PCBs in place within the array. These tabs are routed through a CNC (Computer Numerical Control) machine to separate the flex PCBs from the panel.
Each of these methods depends on factors like the design of the PCB array, the intended use of the flex PCBs, and the type of material used. The choice of separation technique will influence factors such as precision, ease of assembly, and manufacturing cost.
Once the separation process is complete, the individual flex PCBs are ready for final inspection, testing, and packaging.
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