Blind and Buried VIA PCB
Posted: May 14, 2022
By: Bonnie
High-density multilayer PCBs may have microvias: blind vias are exposed only on one side of the board, while buried vias connect internal layers without being exposed on either surface.
Thermal vias carry heat away from power devices and are typically used in arrays of about a dozen.
Contents
1 Definition of Blind and Buried VIA PCB
2 What is blind via in PCB?
3 Buried Via
4 Key benefits
5 Blind and Buried VIA PCB manufacturer
Definition of Blind and Buried VIA PCB
Blind and buried vias are used to connect between layers of a PCB where space is at a premium. A Blind Via connects an outer layer to one or more inner layers but does not go through the entire board. A Buried Via connects two or more inner layers but does not go through to an outer layer.
Blind and buried vias are used to connect between layers of a PCB where space is at a premium. A Blind Via connects an outer layer to one or more inner layers but does not go through the entire board. A Buried Via connects two or more inner layers but does not go through to an outer layer. Blind vias are copper-plated vias that are only interconnected with an outer layer of the PCB. However, it is important to know that the hole does not reach the circuit board all the time, making it "blind" or "invisible" to the naked eye. The through holes between the inner layers cannot be seen after being pressed, so there is no need to occupy the area of the outer layer. The upper and lower sides of the hole are in the inner layer of the board, in other words, they are buried inside the board. The hole of the blind hole must be defined with a separate drill file, and the ratio of the hole diameter to the drill bit diameter must be less than or equal to 1. Each hole has an inner layer. The smaller the hole, the smaller the distance between the outer layer and the corresponding inner layer.
Buried vias are used to create connections of the inner layers, which have no contact with the outer layers. The holes for each connection level must be defined as a separate drill file. The ratio of hole depth to drill diameter (aspect ratio) must be ≤ 12. The buried via connects at least two layers without reaching the outer edge of the board. Therefore, it is buried inside the circuit and completely inside. Applied to the connection between the surface layer and one or more inner layers, one side of the hole is on one side of the board, and then it reaches the inside of the board. Because these buried vias are used to connect different parts of the inner layer of the prototype circuit board, each hole must be made from a separate drilling file.
If the PCB space is limited, or with tight plated through hole constraints. Blind and Buried Vias meet the density constraints of lines and pads on a typical design without increasing the layer count or board size.
A blind via never goes all the way through a circuit board. In terms of design, blind vias are defined in a separate drill file.
Blind and Buried VIA PCB manufacturer
AiPCBA has capability of manufacturing Blind and Buried VIA PCB. Although this technique has more costs, we have experience of sourcing good factory to reduct price.
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