blind and buried vias
KINGSIGNAL'S BLIND AND BURIED VIAS
Blind and buried vias are essential techniques for creating connections between layers of a printed circuit board (PCB), especially when maximizing space is a priority. Typically, a blind via links the outermost layer to one or more inner layers without passing through the entire PCB.
In contrast, buried vias connect two or more inner layers without reaching the outer layer. While these concepts might seem straightforward, there are various rules and limitations that dictate the use of these vias, making the choice between buried and blind vias important.
Kingsignal can evaluate your engineering requirements, spatial constraints, and the functional needs of your PCB to help you minimize costs using buried and/or blind vias.
BURIED VIAS V.S. BLIND VIAS
PCB blind vias are holes that you can plate with copper and that can interconnect an outer layer with most internal layers of your board. Similar to buried vias, there are buried via that has the same design but it can only connect internal layers.
That will be nice but it also has some limitations that we should take into consideration. Vias must only divide an even number of copper layers, may not begin at the bottom side of your core or finish on the top side of your core and blind or buried vias may not finish in other vias or at a junction with them. The exception to this is if your via is enclosed entirely within the terminal point, and that does come at a cost, although it is not necessarily the most effective configuration.
ADVANTAGES
The main benefit you’ll get from blind and buried via fabrication is that you’re able to meet density requirements and constraints for lines and pads on your design without increasing the overall layer count or the size of your board. They’re a great option for saving space and meeting extremely tight design tolerances.
Vias also help designers manage the hole-to-pad ratio and limit the chance of breakout.
DISADVANTAGES
Cost is the main issue with blind and buried vias. Comparatively, you’ll typically see a reduced cost with buried vias vs. blind vias, but using either will likely increase the cost of your board significantly. The cost rises because you’re making a more complex board and introducing more steps in the manufacturing process, while making testing and precision checks more frequently.
Peck Drilling Blind Vias
Drill depth is crucial when creating vias, as drilling too shallow or too deep can severely affect the board’s performance. Improper depth can also lead to spurs and rough edges, which may cause additional issues.
However, companies can reduce costs by utilizing blind vias created through peck drilling. This technique involves repeatedly plunging the drill into the board to remove material buildup and prevent rough spots. By choosing Kingsignal, a master machinist in peck drilling, you can ensure that air is not trapped during the process, allowing for proper plating and reliable connections to internal layers.
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