How Do Buried Microvias and Microvias Differ From Blind Microvias?

Microvias and Microvias Differ From Blind Microvias

As technology becomes more and more miniaturized, printed circuit board (PCB) designers are increasingly seeking to maximize space by reducing the number of plate through holes in their designs. This is one of the driving forces behind the popularity of buried vias and microvias, which can be used to connect layers without increasing the total number of layers in the PCB or the size of the pads. However, determining the correct type of via to use in a particular design can be confusing, since there are many different types of vias available and each has its own benefits and drawbacks.

While there are several different types of vias, blind and buried vias are two of the most popular. The difference between these two is that a blind via can be filled, while a buried via cannot. This makes a buried via an ideal choice for applications that require the connection of multiple layers, such as a high-density interconnect (HDI) PCB.

In the world of HDI PCBs, a buried via is a plated-through hole that does not extend to the surface of the board. It consists of a stack of internally drilled and etched microvias, each of which is filled with conductive paste and plated to provide an electrical connection.

How Do Buried Microvias and Microvias Differ From Blind Microvias?

The walls of a buried via slope inwards and terminate at the pad on the layer just above it. This prevents the via from being exposed to the outside world and thus protects it from corrosion.

Another important benefit of a buried via is that it reduces the aspect ratio of the PCB, allowing the board to be thinner than if it was not using this technique. In turn, this can lower the manufacturing cost because the board requires less material.

A buried via can be stacked with other microvias, which is useful in forming connections across several layers. To ensure that these connections are reliable, the buried microvias must be drilled and plated before each of them is filled. However, there is a risk that the first microvia in the stack will fail due to a poor connection with the surface of the next layer. This is why it is important to use staggered microvias, where each of the vias in the stack are offset from each other.

Buried microvias are a good choice for applications that require multiple layers because they can be stacked with other microvias to form an extremely large structure. Staggered microvias also help to reduce the aspect ratio of a multilayer PCB, making them an excellent option for applications that require multiple layers of high-density connections. Regardless of the specific type of microvia you choose, be sure to consult with your PCB manufacturer to understand how best to use them in your design to avoid any costly mistakes that may occur during fabrication.

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