concept of a buried via hole
A via hole is an important component of multilayer PCBs that allows signals and power to travel between layers. They can be classified into three types: plated through holes, blind vias, and buried via holes. While a plated through hole is a hole that extends through the whole layer of the board, blind and buried vias are internal to the PCB and do not connect with the outer layers. The manufacturing process of a buried or blind via is more challenging and time-consuming than that of a standard via.
Buried vias are copper plated connections between the inner layers of a multilayer PCB that do not emerge on either the top or bottom surfaces. These are used mainly to connect inner-layer signal traces to reduce the chance of interference with outside circuits and are commonly employed in HDI (high-density) PCBs.
While through-hole vias are more common than blind or buried vias, each type of via has its own unique advantages and disadvantages that can influence your design decision. When choosing which type of vias to use in your circuit board, consider the layout and requirements of your design. Here are some of the basics of these three types of vias:
A buried via hole is a copper plated connection between the inner layers of a multilayer printed circuit board that does not emerge on either the top or the bottom surface. The drilled holes are plugged with solder mask to prevent shorting during wave soldering and to protect the solder ball from flux residue. Buried vias can be found in HDI PCBs, and they are often utilized for escape routing, which is a routing technique that helps to simplify the circuit by transferring tracks from one layer to another.
Can you explain the concept of a buried via hole?
The main advantage of a buried or blind via is that it can save space that would otherwise be wasted on outer layers. This can be beneficial if you are designing a high-speed circuit or an application that requires tight control of track lengths.
Another benefit of a buried or blind via is its ability to improve circuit performance. The smaller the hole, the less it will interfere with other circuits on the board and the more signal transmission will be possible. However, it is important to note that a smaller hole will also increase parasitic capacitance.
A buried or blind via is not the same as a microvia, which are a more compact alternative to blind and buried vias. A microvia is a small hole that connects neighboring inner layers. The production of microvias is more complicated than that of a standard via and involves partial bonding, followed by an electroplating treatment. It is also more expensive than the production of a through-hole or a blind via. Despite their added cost, these microvias are still more efficient and more reliable than a traditional through-hole via. They are often utilized in high-speed and high-density applications.
