What is via in PCB?

Vias are the most common holes in PCB production. They connect the different layers of the same network but are usually not used for solder components. Vias can be divided into three types: through holes, blind vias, and buried vias. The details information for these three vias is as below:

Blind vias

Blind vias are small holes that connect one layer of the PCB to another without passing through the entire board. Blind vias enable designers to create complex and densely packed PCBs more efficiently and reliably than conventional methods. With blind vias, designers can create multiple levels on a single board, reducing component costs and making for faster production times. Also, the depth of the blind via usually not over a specific ratio (aperture). This production method must pay special attention to the drilling depth control (Z axis). It should be appropriated. If you ignore it, it won’t be easy to electroplate in the hole in the plating process. The other way to make blind via, you can also drill the holes for the circuit layer that needs to be connected first at the time of making individual circuit layers, then stick each layer together ( for example, blind via from L1-l4, you can drill L1 and L2, L3 and L4 first, then attach all four-layer). Still, this method needs an exact positioning and alignment device.

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    Buried vias

    Buried vias connect the inner layer circuit in PCB. They can connect any inner layer but not through to the outer layer, so you can not see it from the outer layer like buried inside the PCB. And they are also used in inner signal interconnection. People familiar with the PCB industry may share their views, “Buried vias can reduce the probability of signal interference, keep the continuity of the characteristic impedance of the transmission line, and save the wiring space at the same time, right?” Yes, indeed. That’s why they are suitable for high-density and high-speed PCB. Buried via can not be drilled after lamination. We have to drill at individual circuit layers. It will take more time than through holes, and blind vias, so buried via costs are the highest. Buried via typically use in high-density PCB to increase the usable space of other circuit layers.

    Through holes

    Through holes are used to connect all layers through the top layer and bottom layer. Plating copper inside holes can be used in internal interconnection or as a component positioning hole. The purpose of through holes is to allow for the passage of electrical wiring or other components through a surface. Through holes provide a means to mount and secure electrical connections on printed circuit boards, wires or similar substrates that require an attachment point. They are also used as anchors and fasteners in industrial products such as furniture, shelving, and medical equipment. Additionally, through holes can provide pass-through access for threaded rods in machinery or structural elements. Furthermore, the process of plugging through holes is required. Viasion summarizes the following requirements for plugging through holes.

    The primary use for via is an electrical connection. The size is smaller than other holes that use for solder components. The holes used for solder components will be bigger. In PCB production technology, drilling is a fundamental process, and one can not be careless about it. The circuit board can’t provide electrical connection and fixed device functions without drilling the required through holes in the copper-clad plate. If an improper drilling operation causes any problem in the process of through holes, it may affect the use of the product, or the whole board will be scrapped, so the drilling process is critical.

    The drilling methods of vias

      There are mainly two drilling methods of vias: mechanical drilling and laser drilling.


    Precautions for PCB via design

    Mechanical characteristics of PCB through hole

    Why PCB vias must be plugged?

     Here are some reasons why PCB vias must be plugged, summarized by Viaison: 


    Therefore, PCB vias must be plugged to prevent any electrical malfunctions or damage to the PCB.


    In a nutshell, PCB vias are essential parts of PCBs, allowing them to route signals effectively between layers and connect different board elements. By understanding their various types and purposes, you can ensure that your PCB design is optimized for performance and reliability.

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