maximum aspect ratio for blind vias
As the name suggests, blind vias are a PCB connection between inner layers that doesn’t pass all the way through the board. This allows designers to reduce board size by eliminating the need for through-hole vias and opens up a range of new routing alternatives. They’re common in high density interconnect (HDI) PCBs as they provide a route between layers that would otherwise be unconnected.
When designing a circuit board with blind vias, there are a few important things to keep in mind. First and foremost, they are much more prone to failure than standard through-hole vias. This is due to the stress placed on them during the manufacturing process. Secondly, they are more complex to design and require a higher level of accuracy during the PCB layout phase. This is due to their smaller diameter and the difficulty of placing them at a precise depth within the PCB.
Fortunately, there are some methods that can be used to improve the reliability of these holes. For example, one method is to drill the via off to the side of the pad rather than in the center of it. This alleviates the problem of air bubbles forming under the solder balls, which can cause them to fail.
What is the maximum aspect ratio for blind vias?
Another option is to use microvias, which are very small vias that allow for more copper plating in a smaller area. However, these aren’t always a viable option for high-layer boards because they can cause issues with signal quality and make it difficult to ensure a uniform plating thickness across the board.
A third method involves drilling a large hole and then etching away the material surrounding it. This can be an effective method for reducing the number of microvias in a circuit board, but it can also create issues with the integrity of the layers underneath the vias. Therefore, it’s important to carefully consider the overall design before choosing a particular via manufacturing method.
The maximum aspect ratio for a blind via is the ratio of the hole’s drill diameter to its depth. This is important because it affects the ability of the drilled hole to conduct signals. Aspect ratios above this limit may result in signal distortion or degradation, or even the occurrence of short circuits.
In general, it’s best to define the size of your vias early in the design process. This will help prevent the errors that can be caused by rigid design patterns and ensure that your board’s internal connections are as robust as possible. The PCB experts at Altium can assist you with defining your via specifications and ensuring that your designs are ready for the manufacturing stage. Contact us today to get started.
