What are the Differences Between Blind Vias and Buried Vias?

PCB Basics 
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Editorial Team - PCB Directory

May 23, 2023

In PCB (Printed Circuit Board) design, a via refers to a hole drilled in the board that electrically connects two or more layers of the board. Vias are used to create a conductive path between layers of a PCB, and they can be plated with metal to ensure a continuous electrical connection between the layers. Vias can be of different types, such as through-hole vias, blind vias, and buried vias, each with a different purpose and function in the PCB design. Vias are essential to modern PCB design, allowing designers to create complex and high-density circuits on a single board

 A computer-generated cross-sectional view of a multi-layered PCB: 1. Blind Vias; 2. Buried Vias; 3. Through-Hole Vias 

What are Blind Vias?

Blind vias are an essential component of modern printed circuit board (PCB) design, specifically multi-layered PCBs. They are small holes that are drilled into the board to connect the different layers of a PCB. Blind vias are called so because they only go partway through the board, stopping at a specific layer rather than running through the entire board. This allows for the creation of more complex and compact board layouts, making them ideal for modern electronics with smaller form factors. Blind vias are used to route signals and power between layers while minimizing the number of layers needed, reducing the overall cost and size of the board.

What are Buried Vias?

Buried vias are an essential component of modern printed circuit board (PCB) design, specifically multi-layered PCBs. They are small holes that are drilled into the board to connect the different layers of a PCB. Buried vias differ from blind and through-hole vias because they are located between two inner layers of the PCB and do not penetrate through the surface of the board. This allows for the creation of more complex and compact board layouts, making them ideal for modern electronics with smaller form factors. Buried vias just like Blind Vias are used to route signals and power between layers while minimizing the number of layers needed, reducing the overall cost and size of the board.

Blind Vias and Buried Vias: The Differences

While both blind and buried vias serve the same purpose, they differ in how they are used and their construction. Let’s have a look at that:

Parameter

Blind Vias

Buried Vias

Visibility

Blind vias are visible from one side of the board

Buried vias are entirely hidden between the layers of the board

Manufacturing Complexity

The manufacturing process of Blind Vias is simpler compared to buried vias

Buried Vias require a complex manufacturing process. They involve drilling between inner layers and filling with copper or a conductive paste

Cost of Production

Blind vias are less expensive

It is more expensive to manufacture buried vias

Routing Options

Blind Vias provide fewer routing options as they have to be routed to the surface of the board

Buried vias provide more routing options as they do not need to be routed to the surface layers of the board.

Design Flexibility

Blind Vias offer fewer flexibility options as opposed to buried vias

Buried vias offer more design flexibility as they reduce the number of drilled holes and provide better signal integrity.

Space Efficiency

Blind vias can help save space on the board by allowing surface-mounted devices to be connected to the inner layers of the board.

SMT is not possible for buried vias PCBs

Conclusion

In conclusion, both blind and buried vias are essential for high-density PCB designs. Blind vias are used to connect surface-mounted devices to inner layers of the board, while buried vias are used to create a more compact design and allow for more inner layer routing options. While blind vias are visible from one side of the board, buried vias are entirely hidden between the layers of the board. The choice between the two depends on the specific requirements of the design.

Click here to learn more about Blind Vias.

Click here to learn more about Buried Vias.

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