Buried Via Improve PCB Reliability
A buried via is a type of hole in a PCB that connects two or more inner layers without connecting to the outer layer. It is used in multilayer PCBs to increase available space on the outer layers for other functions, such as placing components or routing traces.
The use of buried vias has several advantages, including increased routing density, better impedance control, and improved reworkability. However, there are some important considerations that must be made when using these holes in your design.
Vias are crucial to a circuit board’s functionality, allowing signal transmission and power to be routed throughout the board. There are three main types of vias: through-hole, blind, and buried. Despite their different characteristics, these vias all serve the same purpose of connecting circuit boards to each other and to external devices.
Through-hole vias are drilled through the copper layers of the PCB, creating a pathway for electrical signals and power to travel through the circuit. They can be placed on the top, bottom, and internal layers of a PCB. Depending on the design of a PCB, some vias may be more useful than others for specific tasks. For example, if a through-hole via is located close to an edge of the board, it may be more difficult to access than a through-hole via that is further away from the edge.
How Can a Buried Via Improve PCB Reliability?
Both blind and buried vias are used in the creation of PCBs because they allow for better connectivity between different layers within the circuit board. This can be especially beneficial for complex or high-speed circuits that require more connections. Additionally, these vias can help minimize the number of crossing and bent wires in a circuit, which increases reliability.
Compared to through-hole vias, blind and buried via have a smaller diameter. They also have the added benefit of being able to improve signal transmission speed by shortening the length of the circuit’s path. This is particularly important for high-speed digital and microwave circuits.
These holes are also more complex to make than through-hole vias, as they must be drilled in the inner layers of the PCB before lamination. This requires partial bonding of the inner layers, drilling and plating the drilled area, and then lamination for the complete board. This process is more costly than traditional multilayer PCB production, but it allows for greater flexibility and adaptability to different application scenarios.
In order to manufacture a PCB with blind and buried vias, manufacturers must first prepare the pre-preg and copper foil. They then apply heat and pressure to the core to bond the sheets together, drill and plate the bare copper layers, and then laminate the final PCB. The manufacturing of a PCB with these vias is much more time-consuming and expensive than producing a normal multilayer PCB, but it is essential to high-performance applications.
