What are Array Rails
Array Rails are frames made of the same PCB material that enclose the array of PCBs during panelization. These rails serve multiple purposes in the assembly process. Firstly, they provide support and structural integrity to the panel, ensuring that the individual PCBs within the array remain stable and secure. This is particularly important during transportation and handling, as it helps prevent any movement or flexing of the PCBs that could potentially damage the electronic components.
Additionally, array rails enable the safe and efficient transportation of the panel through conveyor belts and SMT (Surface Mount Technology) equipment. The rails act as guides, allowing the equipment to securely grab and transport the panel without causing any harm to the delicate components placed on the printed circuit boards.
When incorporating array rails into a PCB panel, several factors need to be considered. The width of the rails is an important aspect, as it determines the strength and stability of the panel. It is crucial to strike a balance between providing sufficient width for support and minimizing the board area required, as wider rails can increase fabrication costs.
Furthermore, the inclusion of tooling holes is recommended. These non-plated holes, typically three or four in number, aid in the precise alignment and positioning of the panel during the assembly process. They ensure that the panel is correctly oriented for component placement, contributing to the overall accuracy of the assembly.
To enhance the assembly process further, it is advisable to incorporate fiducial marks on the array rails. Fiducial marks are plated pads that lack solder paste and serve as reference points for the pick-and-place machine vision system. By utilizing these marks, the machine can accurately determine the position and orientation of the PCBs within the panel, facilitating precise component placement during assembly.
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