Buried Via Holes Improve the Density of a PCB Design
As technology advances, PCB designers are continually looking for ways to increase the density of a PCB design. This requires finding more space for components and traces, as well as minimizing impedance issues and electromagnetic interference (EMI). Buried via holes are an effective tool in achieving this goal, providing additional connection points in a board without increasing its overall size. This article discusses how buried via holes improve the density of a PCB design and their benefits in multilayer boards.
A buried via is a plated through hole (PTH) that connects internal layers of a printed circuit board but does not extend to the outer surfaces. They are not visible from the outside of a multilayer board and can only be traced through its documentation (layout or schematic). Buried vias enable designers to reduce the number of PTH through-holes required, improving signal integrity and reducing the risk of interference.
buried via hole can be made either after or before multilayer lamination. In the former case, a photosensitive resin is laminated to a core that has holes already drilled in it. The holes are then etched, and copper is plated in them. This produces a thin layer of copper on the inner layers and the PCB’s outer surface, covering both the hole’s external surfaces and the surrounding areas. In the latter case, a thin layer of copper is deposited on the core before it is pressed into a multilayer stack. The holes are drilled, and then a photosensitive material is laminated over the core to protect them from damage during the manufacturing process.
How Do Buried Via Holes Improve the Density of a PCB Design?
In addition to lowering component and trace sizes, buried vias also help to reduce the cost of a PCB by allowing it to be fabricated in fewer layers. Adding more layers to a PCB increases the amount of copper, dielectric materials and prepreg used, as well as the time and costs associated with preparing and laminating each layer. However, by using buried vias, manufacturers can significantly reduce the number of layers needed to provide adequate functionality and performance.
The primary advantage of buried vias is their ability to make connections in locations where traditional through-hole holes cannot. By enabling a higher routing density in the inner layers of a PCB, designers can maximize the use of space for power distribution, signal routing and ground planes. This can lead to reduced costs, improved reliability and increased functionality in the final product.
There are several ways that buried vias can be manufactured, including through-hole drilling, plasma etching and photo-via tenting. These methods require more equipment and skill than conventional manufacturing processes, but they offer the advantages of higher routing density, reduced impedance and better reworkability. However, the most important factor for making a successful buried via design is careful planning and consideration of its placement. If a buried via is not properly placed, it can cause EMI and signal degradation. The best way to avoid this is by working closely with a professional PCB manufacturer during the design and layout phase of a project.