A via (via) is a copper foil hole used to connect or link conductive patterns between different layers of a circuit board. However, it is a copper-plated hole that cannot be used to insert component leads or other reinforcing materials. A printed circuit board (PCB) is formed by stacking many layers of copper foil. The copper foil layers cannot communicate with each other because an insulating layer is placed between each layer. Therefore, they need to be linked by vias (vias), hence the Chinese name "through-hole" (导通孔).
The vias on circuit boards must be plugged to meet customer requirements. In a process that changes the traditional aluminum sheet plugging method, solder mask and via plugging on the circuit board surface are completed using white mesh, making production more stable, quality more reliable, and application more comprehensive. Visors facilitate circuit interconnection and conduction. With the rapid development of the electronics industry, higher demands are being placed on the manufacturing processes and surface mount technology of printed circuit boards (PCBs).
The via plugging process was developed to address this need, while also meeting the following requirements:
As long as there is copper inside the hole, the solder resist can be filled or not.
The holes must contain tin-lead with a certain thickness requirement (4um) to prevent solder resist ink from entering the holes and causing solder beads to accumulate inside.
The vias must be plugged with solder resist ink, be opaque, and free of solder rings and beads. They must also be flat.
A blind via is a plated hole used to connect the outermost layer of a printed circuit board (PCB) to an adjacent inner layer. Because the other side is not visible, it is called a blind through-hole. Blind vias are used to increase the space utilization between circuit layers on the board. A blind via is essentially a through-hole leading to the surface of the printed circuit board.
Blind vias are located on the top and bottom surfaces of a circuit board and have a certain depth. They are used to connect surface layer traces to underlying inner layer traces, and the depth of the via generally follows a specified ratio (hole diameter). This manufacturing method requires special attention; the drilling depth must be just right, otherwise it will cause difficulties in electroplating inside the hole. Therefore, few factories use this manufacturing method. It is also possible to pre-drill holes in the individual circuit layers that need to be connected and then glue them together, but this requires more precise positioning and alignment devices.
A buried via is a connection between any circuit layers inside a printed circuit board (PCB), but it is not conductive to the outer layers; that is, it is a via that does not extend to the surface of the circuit board.
This manufacturing process cannot be achieved by gluing the circuit board together and then drilling. Drilling must be performed on individual circuit layers first, followed by partial gluing of the inner layers, electroplating, and finally, full gluing. Because this process is more labor-intensive than traditional vias and blind holes, it is also the most expensive. This manufacturing process is typically used only for high-density circuit boards to increase the space utilization of other circuit layers.
Drilling is a crucial process in printed circuit board (PCB) manufacturing. Simply put, drilling involves creating vias on a copper-clad laminate to provide electrical connections and secure components. Incorrect drilling can cause problems in the via process, preventing components from being properly mounted on the circuit board. This can range from affecting the board's usability to rendering the entire board unusable. Therefore, drilling is an extremely important step.
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